The municipality was established in the 1815 under the Spanish colonial government in the country. The municipality got its name from the diligent and hardworking people, working hand in hand especially during the agricultural harvest season. "Pinamungajan", which originated from the Visayan word Pinamuhuan, meaning a worker share for his effort during a farm harvest. Over time the Pinamuhuan eventually changed to the current name of the municipality.
The mayor, Gaye Yapha, is the daughter of former congressman Dr. Antonio P. Yapha.