His exact birth and death years are not confirmed by primary sources. Born as the second son of Oyama Takatomo, a Kozuke warlord, he was originally named Oyama Shigetomo. He succeeded Tomioka Hidechika as head of the Tomioka clan, taking the name Tomioka Hidetaka, and became lord of Koizumi Castle. In 1567 he allied with Hojo Ujiyasu and thereafter served as a leading local vassal of the Late Hojo clan in the Agatsuma and Ora region. During the 1578 Otate no Ran he marched to relieve Uesugi Kagetora, and in 1580 he fought Takeda forces in Suruga. At the 1583 Battle of Numajiri he repelled repeated attacks by the forces of Satake Yoshishige and Sano Munetsuna, earning a commendation from the Hojo. During the 1590 Siege of Odawara he is said to have defended Nitta Kanayama Castle.

A steadfast local lord who served the Hojo faithfully and repeatedly distinguished himself in defensive battles, personally taking the field whenever his overlords faced crisis.

As the Sengoku-era lord who defended Koizumi (Tomioka) Castle, his stronghold survives today as Shironouchi Park, designated a historic site by Oizumi Town.