Hiroki Mizuhara (水原 大樹, Mizuhara Hiroki, born January 15, 1975) is a former Japanese football player.

Mizuhara was born in Heguri, Nara on January 15, 1975. After graduating from high school, he joined Nagoya Grampus Eight in 1993. On March 25, 1995, he debuted as substitutes against Júbilo Iwata.^[1][2] However he could only play this match behind Yuji Ito until 1998. In 1999, he moved to Japan Football League (JFL) club Honda and played many matches. In 2000, he moved to JFL club Yokohama FC. He played as regular goalkeeper. The club won the champions in 2000 and was promoted to J2 League from 2001. In 2004, he moved to J1 League club Tokyo Verdy. On May 14, 2005, he played against Kashiwa Reysol in J1 League instead Yoshinari Takagi who was suspended.^[3][4] This match was his match in J1 for the first time in 10 years. However he could hardly play in the match behind Takagi in 3 seasons until 2006. In 2007, he moved to Regional Leagues club New Wave Kitakyushu (later Giravanz Kitakyushu). He played as regular goalkeeper and the club was promoted to JFL in 2008 and J2 in 2010. However he lost position in 2011 behind Yuya Sato who came the club in 2011. In 2012, Mizuhara moved to JFL club Kamatamare Sanuki. In February, he announced his retirement.^[5] However he joined Prefectural Leagues club Veertien Kuwana in May 2013 and he played for the club in 1 season.