PURPOSE: To perform a trimming operation efficiently by a method wherein a film resistor for trimming use is formed to be trapezoidal or hook-shaped and a region where a current density is low is adjusted fine.

CONSTITUTION: For example, when a trimming operation is performed by using a trapezoidal film resistor 12, the resistor is first adjusted coarsely by means of an L-shaped cut 13 for coarse adjustment use. Then, a cut 14 for fine adjustment use is executed from an oblique side in a region 12a where a current density is low. The resistor can be adjusted fine in a state that the change rate of a resistance value due to a trimming distance is low, and its fine adjustment is completed while an ordinary straight cut at a first working speed is used. Thereby, it is possible to efficiently perform the trimming operation whose working speed is fast and which can perform the high-accuracy fine adjustment.