Masahiro Shimizu (born November 22, 1964) is a Japanese former professional Grand Prix motorcycle road racer.
Originally from Fujisawa, Kanagawa Prefecture, Shimizu won the 1987 250cc All Japan Road Race Championship.
He began his Grand Prix career with a win in 1987.
His best season was in 1991, when he finished fifth in the 250cc world championship, riding on a Honda.