Olivine formed by the reaction antigorite+brucite=2 olivine+3 water from the Ryumon peridotite body, a regionally metamorphosed serpentinite of the Sanbagawa metamorphic belt, exhibits zoning with Fe, Mn and Ni-rich core and Mg-rich rim. From the core to the rim, X_Mn decreases at much higher rate than X_Ni does. The chemical relations between olivine and coexisting antigorite and brucite suggest that the zoning was formed by fractional crystallization of olivine from antigorite and brucite at the time of progressive metamorphism. The higher decreasing rate of X_Mn than X_Ni can be explained by the smaller values of K_D^anti-ol _Mn-Mg and K_D ^bru-ol _Mn-Mg than K_D^anti-ol _Ni-Mg and K_D^bru-ol _Ni-Mg, respectively. This type of zoning may be characteristic of the zoning of olivine crystallized from serpentine. The zoned olivine suggests that local equilibrium was maintained even at low-grade in metamorphosed serpentinite.