PURPOSE: To allow convenient regulation of the inductance of a film inductor by moving a piece along a circuit pattern while measuring the inductance of film inductor, determining a position where the film inductor has a predetermined inductance, and fixing the piece thereat.

CONSTITUTION: A measuring unit 10 is connected with a film inductor comprising upper and lower electrodes and a ferrite piece 9 is prepared. The ferrite piece 9 is place at a point on an overcoat glass 4 and then it is shifted slowly while measuring the inductance of a film inductor. The ferrite piece 9 is bonded through a dielectric adhesive, e.g. epoxy adhesive, onto the overcoat glass 4 at a point where a desired inductance is obtained. Since the flux of film inductor flows into the ferrite piece, the inductance of film inductor increases over the original value.