Willy Loman returns home exhausted after a cancelled business trip. Worried over Willy's state of mind and recent car accident, his wife Linda suggests that he ask his boss Howard Wagner to allow him to work in his home city so he will not have to travel. Willy complains to Linda that their son, Biff, has yet to make good on his life. Despite Biff's promise as an athlete in high school, he flunked senior-year math and never went to college.
Biff and his brother Happy, who are temporarily staying with Willy and Linda after Biff's unexpected return from the West, reminisce about their childhood together. They discuss their father's mental degeneration, which they have witnessed in the form of his constant vacillations and talking to himself. Willy walks in, angry that the two boys have never amounted to anything. In an effort to pacify their father, Biff and Happy tell Willy that Biff plans to make a business proposition the next day.
The next day, Willy goes to ask his boss, Howard, for a job in town while Biff goes to make a business proposition, but neither is successful. Willy gets angry and ends up getting fired when the boss tells him he needs a rest and can no longer represent the company. Biff waits hours to see a former employer who does not remember him and turns him down. Biff impulsively steals a fountain pen. Willy then goes to the office of his neighbor Charley, where he runs into Charley's son Bernard (now a successful lawyer); Bernard tells him that Biff originally wanted to do well in summer school, but something happened in Boston when Biff went to visit Willy that changed his mind.
Happy, Biff, and Willy meet for dinner at a restaurant, but Willy refuses to hear bad news from Biff. Happy tries to get Biff to lie to their father. Biff tries to tell him what happened as Willy gets angry and slips into a flashback of what happened in Boston the day Biff came to see him. Willy had been having an affair with a receptionist on one of his sales trips when Biff unexpectedly arrived at Willy's hotel room. A shocked Biff angrily confronted his father, calling him a liar and a fraud. From that moment, Biff's views of his father changed and set Biff adrift.
Biff leaves the restaurant in frustration, followed by Happy and two girls that Happy has picked up. They leave a confused and upset Willy behind in the restaurant. When they later return home, their mother angrily confronts them for abandoning their father while Willy remains talking to himself outside. Biff goes outside to try to reconcile with Willy. The discussion quickly escalates into another argument, at which point Biff forcefully tries to convey to his father that he is not meant for anything great, insisting that both of them are simply ordinary men meant to lead ordinary lives. The feud culminates with Biff hugging Willy and crying as he tries to get Willy to let go of the unrealistic expectations that he still has for him and to accept him for who he really is. He tells his father he loves him.
Rather than listen to what Biff actually says, Willy thinks his son has forgiven him and thinks Biff will now pursue a career as a businessman. Willy kills himself, intentionally crashing his car so that Biff can use the life insurance money to start his business. However, at the funeral Biff retains his belief that he does not want to become a businessman. Happy, on the other hand, chooses to follow in his father's footsteps.
William "Willy" Loman: The salesman. He is 63 years old and very unstable, tending to imagine events from the past as if they are real. He vacillates between different perceptions of his life. Willy seems childlike and relies on others for support. His first name, Willy, reflects this childlike aspect as well as sounding like the question "Will he?" His last name gives the feel of Willy's being a "low man," someone low on the social ladder and unlikely to succeed; however, this popular interpretation of his last name has been dismissed by Miller.
Linda Loman: Willy's wife. Linda is passively supportive and docile when Willy talks unrealistically about hopes for the future, although she seems to have a good knowledge of what is really going on. She chides her sons, particularly Biff, for not helping Willy more, and supports Willy lovingly despite the fact that Willy sometimes treats her poorly, ignoring her opinions over those of others. She is the first to realize that Willy is contemplating suicide at the beginning of the play, and urges Biff to make something of himself, while expecting Happy to help Biff do so.
Biff Loman: Willy's older son. Biff was a football star with lots of potential in high school, but failed math his senior year and dropped out of summer school when he saw Willy with another woman while visiting him in Boston. He wavers between going home to try to fulfill Willy's dream for him as a businessman or ignoring his father by going out West to be a farmhand where he is happiest. He likes being outdoors and working with his hands, yet wants to do something worthwhile so Willy will be proud. Biff steals because he wants evidence of success, even if it is false evidence, but overall Biff remains a realist and informs Willy that he is just a normal guy and will not be a great man.
Harold "Happy" Loman: Willy's younger son. He's lived in the shadow of his older brother Biff most of his life and seems to be almost ignored, but he still tries to be supportive towards his family. He has a very restless lifestyle as a womanizer and dreams of moving beyond his current job as an assistant to the assistant buyer at the local store, but is unfortunately willing to cheat a little in order to do so, by taking bribes. He is always looking for approval from his parents, but rarely gets any, and he even goes as far as to make things up just for attention, such as telling his parents he is going to get married. He tries often to keep his family's perceptions of each other positive or "happy" by defending each of them during their many arguments, but still has the most turbulent relationship with Linda, who looks down on him for his lifestyle and apparent cheapness, despite his giving them money.
Charley: Willy's wisecracking yet understanding neighbor. He pities Willy and frequently lends him money and comes over to play cards with Willy, although Willy often treats him poorly. Willy is jealous of him because his son is more successful than Willy's. Charley offers Willy a job many times during visits to his office, yet Willy declines every time, even after he loses his job as a salesman.
Bernard: Charley's son. In Willy's flashbacks, he is a nerd, and Willy forces him to give Biff test answers. He worships Biff and does anything for him. Later, he is a very successful lawyer, married, and expecting a second son ‒ the same successes that Willy wants for his sons, in particular Biff. Bernard makes Willy contemplate where he has gone wrong as a father.
Uncle Ben: Willy's older brother who became a diamond tycoon after a detour to Africa. He is dead, but Willy frequently speaks to him in his hallucinations of the past. Ben frequently boasts, "when I was seventeen I walked into the jungle, and when I was twenty-one I walked out. And by God I was rich." He is Willy's role model, although he is much older and has no real relationship with Willy, preferring to assert his superiority over his younger brother. He represents Willy's idea of the American Dream success story, and is shown coming by the Lomans' house while on business trips to share stories.
Miss Francis: A woman with whom Willy cheated on Linda.
Howard Wagner: Willy's boss. He was named by Willy, but sees Willy as a liability for the company and fires him, ignoring all the years that Willy has given to the company. Howard is extremely proud of his wealth, which is manifested in his new wire recorder, and of his family.
Jenny: Charley's secretary.
Stanley: A waiter at the restaurant who seems to be friends or acquainted with Happy.
Miss Forsythe: A girl whom Happy picks up at the restaurant. She is very pretty and claims she was on several magazine covers. Happy lies to her, making himself and Biff look like they are important and successful. (Happy claims that he attended West Point and that Biff is a star football player.)