To provide an insulation film manufacturing method which can attain an increase in withstand voltage of an insulation film, a reaction device, a power generation device and an electronic apparatus.

A microreactor 1 for causing a reactant to react comprises a top plate 2 and a bottom plate 3 or the like which are metallic substrates. An R2O3 film (Y2O3 film) having the crystalline structure of a rare earth element R is deposited, as an insulation film 31, between the bottom plate 3 and a thin film heater 32 provided on its surface. The R2O3 film is formed by depositing an R film on the surface of the bottom plate 3, hydrogenating it to form an RH2 film, and further oxidizing it.