PURPOSE: To provide an operation trimming method of a hybrid integrated circuit capable of reducing trimming time dramatically with regards to an operation timing method which controls each operation characteristic by trimming in the hybrid integrated circuit.

CONSTITUTION: A measurement system 22 of resistant values equipped with a trimming device is used for a means to measure DC current of a hybrid integrated circuit. When measuring electric signals other than DC voltage, a converter 7 which converts electric signals into DC voltage is inserted between a probe 21 and the measurement system 22, thereby constituting the trimming device.