Ujimasa succeeded the territory expansion policy from his father, Ujiyasu HOJO, and achieved the biggest territory in the clan's history, but the rise of Hideyoshi TOYOTOMI led to the Siege of Odawara.
父・北条氏康の後を継いで北条氏の勢力拡大に務め最大版図を築くも、豊臣秀吉の台頭により小田原征伐を招いた。