When Hideyoshi's younger brother, Hidenaga TOYOTOMI, became the lord of Kii Province in 1585 after the conquest of Kishu, Shigeharu was appointed to a position of Karo (chief retainer) of Hiednaga by Hideyoshi at the Osaka-jo Castle in May of the same year, and became the keeper of Wakayama-jo Castle with properties increased to those yielding 30,000 koku (approximately 5,411.7 cubic meters of crop yields) in total.
天正13年（1585年）、紀州征伐の後に秀吉の弟・豊臣秀長が紀伊国の領主になると、同年5月に大坂城で秀吉から秀長の家老職を命ぜられ、3万石への加増を受けて和歌山城代となった。