A chuck for mounting workpiece is disclosed. A chuck for mounting workpiece includes a chuck body; and a base jaw mounted on the chuck body. The chuck body includes an aluminum alloy. The chuck body includes an aluminum alloy having specific gravity smaller than that of alloy steel for machining structural use or carbon steel for machine structure use. Thus, the chuck can be light weight.

A finger includes a pair of overhanging portions that project out laterally from a main body portion. Outer peripheral surfaces of the overhanging portions are made up from five surfaces including upper surfaces, side surfaces, lower surfaces, first end surfaces, and second end surfaces. Crowning is applied to the intersections between these surfaces.