Hidekazu Mashima was born in Yonezawa, Yamagata, Japan. He started getting interested in films because of the influence of friends when he studied law at Kokushikan University in Tokyo. He took acting classes and received the offer of a leading role in Lee Sang Il's graduation project, "Chong" (2000). After his debut, he dropped out of law school regardless of the disagreement of his parents and stayed in Tokyo to keep pursuing his acting career.