To provide an auxiliary implement for making a fine cut of an onion without requiring skill.

An almost semispherical inside space is arranged in an almost semispherical body part, and cutouts are mutually arranged at equal intervals in parallel in the vertical direction over the almost whole of this inside space. A placing table having a dimension coincident with an opening part of the inside space of the body part is prepared, and an object (such as the onion cut in half) is placed on the placing table, and a body is put on the table. A kitchen knife is successively inserted into the cutouts arranged in the body, and the object is cut in the first direction. The fine cut is made by similarly cutting the object in the second direction orthogonal to the first direction by rotating the body part by 90 degrees. A mutually fixing stopper member may be arranged on the body and the placing table.