Disclosed is a soap making split mold composed of a set of splits 1A and 1B adapted to be assembled together to form a molding cavity 1C. The split 1A has a larger surface area in its recess 11A defining part of the cavity 1C than the other split 1B does in its recess 11B defining the other part of the cavity 1C. The ratio of the surface area of the recess 11A of the split 1A to that of the recess 11B of the split 1B ranges from 52:48 to 66:34. Otherwise, the split 1A has a larger surface roughness Ra in its recess 11A defining part of the cavity than the other split 1B does in its recess 11B defining the other part of the cavity. The difference of the surface roughness Ra between the recess 11A and that of the recess 11B is 0.1 to 30 μm.