Despite an eldest son of Yasumichi MATSUDAIRA in a branch family of hatamoto (direct retainers of the bakufu), he was adopted by Yasusada MATSUDAIRA, who did not have a son, and became the third lord of the Mikawa Matsui clan in Hamada Domain.
分家旗本・松平康道の長男だったが、浜田藩主松平康定に子がないため、康定の養子となり、同藩三河松井氏3代目藩主となる。