PURPOSE: To permit a machined object, after it is shorn, to obtain a high accurate shorn surface with no generation of corrugation, warp, etc., by relatively moving shearing blades opposed to each other, in the case of the shearing method executing trimming work for the various machined object.

CONSTITUTION: When a machined object is shorn, a shape of moving blades in a trimming metal mold is determined so that paired shearing blades at least in their two parts may start shearing for the machined object. As one example, the moving blade forms in its both end parts straight edged parts 18a, 18a, and an edged part 18b, placed in an intermediate position, is curved in an arc- shape in the retractive direction for an opposed fixed blade 16. Accordingly, when the moving blade 18 is moved for shearing toward the fixed blade 16, the moving blade 18 comes to perform shearing in two points of the straight edged parts 18a, 18a for the fixed blade 16. By this shearing method, a plate- shaped material, when it is shorn, is prevented from generating a corrugation and a warp, improving dimensional accuracy of a cut surface with no necessity for its correction.