The present inventive concept relates to a hand grinder including a grinder main body, a coupler including a power transfer member coupled to a rotary shaft of a grinder main body and a main body provided between the grinder main body and power transfer member, and a grinding disc including a grinding stone having a hollow disc plate and a coupling portion provided at a central portion of the grinding stone and detachably coupled to the coupler. A plurality of hook steps are radially arranged along an outer circumference of an upper end portion of the power transfer member, and a plurality of coupling pieces are radially arranged on an inner circumference of a central portion of the coupling portion. When the grinding disc is assembled such that the hook steps pass between the coupling pieces and the main body is rotated, a lower surface of the hook steps is placed on an upper surface of the coupling pieces and the grinding disc is fixed to the coupler.