To provide a manufacturing method of an MEMS (micro electro mechanical system) Fabry-Perot element for precisely positioning a parallel member of the Fabry-Perot element.

The respective important process variables for influencing optical output waveform are precisely controlled and plane precision of the surface of the parallel member is secured by manufacturing an interval holding member by utilizing a thin film deposition process and futher controlling thickness of the interval holding member by a film thickness monitor and a spectrum coincident with desired waveform is precisely filtered by the MEMS Fabry-Perot element manufactured by this method.