Mochizuki was born in Shizuoka on July 9, 1973. After graduating from University of Tsukuba, he joined Nagoya Grampus Eight with teammate Takayuki Nishigaya in 1996. The club won the 2nd place at 1996–97 Asian Cup Winners' Cup. In July 2000, he moved to Kyoto Purple Sanga with teammate Takashi Hirano. However the club was relegated to J2 League, he moved to Vissel Kobe in 2001. In 2003, he moved to JEF United Ichihara and in August, he moved to Vegalta Sendai on loan. He returned to JEF United Ichihara in 2004. However he was diagnosed as "Idiopathic Osteonecrosis of Femoral Head" () in 2004. Although he also played for J2 League club Yokohama FC (2005–06), he could hardly play in the match. He retired in August 2006.