The status of ashigaru is thought to have originated during the Heian period from the shimobe (miscellaneous servants and attendants) who served kebiishi (police and judicial chiefs) in the capacity of performing miscellaneous duties and acting as reserve soldiers.
発生は平安時代とされ、検非違使の雑用役・戦闘予備員として従軍した「下部」が足軽の原型とされる。