A method of producing a device including an impedance element provided so as to effect a series resonance, includes a step of connecting connection portions such as terminals or electrodes to be electrically connected in the device, using conductive adhesive resin. This step of connecting connection portions includes a sub-step of applying an alternating current signal which has a frequency lying in close vicinity of a resonant frequency of the device, and which has an enough amplitude to destroy an insulation film parasitically formed in the conductive adhesive resin, to input/output terminals of the device. By executing the sub-step, it is possible to substantially remove a fluctuation in impedance characteristics in dependence on the driving level, and thus to realize a stable operation of the device.