To reduce the grinding resistance, to suppress the generation of the friction heat, to improve the wear resistance of an abrasive grain layer, and to improve the quality of a finished surface of a work.

An abrasive grain layer 11 of a resinoid bonded grinding wheel 10 comprises a resin binder phase 14 whose main plastic substance is a thermosetting resin such as a phenol resin, and superfine abrasive grains 15 of diamond (or CBN, etc.), diffused in this resin binder phase 14. A first filler such as SiO2 17 and a second filler such as CaF2 18 are diffused in the resin binder phase 14. SiO2 17 in the resin binder phase 14 is substantially spherical, and the size of the particles is arranged to form a single diffusion system. The total quantity of SiO2 17 is 5-25 vol.% of the abrasive grain layer 11 in volume ratio, and the grain size of SiO2 17 is 1/20 to 1/4 of the mean grain size of the superfine abrasive grains 15.