Tadakatsu was a Honda clan member as the oldest Anjo fudai (a fudai daimyo who had been serving Ieyasu since he was in Anjo) for the Anjo-Matsudaira family (the head family of the Tokugawa), born the first son of Tadataka HONDA in Kuramae, Mikawa Province (present Okazaki City, Aichi Prefecture) in 1548.
安祥松平家（徳川本家）の最古参の安祥譜代の本多氏で、本多忠高の長男として天文17年（1548年）、三河国蔵前（現在の愛知県岡崎市）で生まれる。