Abstract This paper concerns with an experimental research on the machining of sintered diamond (SD) by electrical discharge machining (EDM). Experiments were carried out with four types of SD, composed of 1-, 3-, 10-, and 20 μm-diameter diamond particles. Tungsten carbide alloy was also tested for comparison. Basic characteristics of micro-EDM were investigated by machining through-holes and trenches in SD plates. Although in some cases unstable machining status was observed, it was found that SD has machining characteristics basically similar to those of tungsten carbide alloy. Machined surfaces were observed in the experiment of machining trenches. The surface roughness of SDs was found to be sufficiently good for micromold applications and the surface property of SDs with large diamond particles was quite different from that of metals.