West Pasaman Regency is a regency of West Sumatra, Indonesia. It has an area of 3,887.77 km², and it had a population of 365,129 at the 2010 Census and 431,672 at the 2020 Census; the official estimate as at mid 2023 was 450,050 - comprising 227,838 males and 222,232 females. The seat of the regency administration is the town of Simpang Ampek.