Recently, the demand for micromachining of hard materials has been increasing. Machining microholes, grooves, and structures in hard materials such as tungsten carbide is very difficult. In this study, the machining characteristics of a microdisk tool for microgroove machining of tungsten carbide were studied. Microtools made of polycrystalline diamond (PCD) were fabricated using wire electrical discharge grinding (WEDG) to machine high-hardness tungsten carbide. Rectangular and V-shaped disk tools were fabricated by WEDG with controlled wire paths. In the micro grooving of tungsten carbide, the effects of capacitance and feedrate on the surface roughness of microgrooves and the wear of disk tools were studied. As the capacitance and feed rate decreased, the surface roughness decreased and no significant wear was observed in the PCD tool. However, an increase in tool edge radius of several micrometers was observed.