A method for manufacturing a micromachine is provided which can remove a sacrifice layer and can perform sealing without using a specific packaging technique. In a method for manufacturing a micromachine (1) including an oscillator (4), a step of forming a sacrifice layer around a movable portion of the oscillator (4); a step of covering a sacrifice layer with an overcoat film (8), followed by the formation of a penetrating hole (10) reaching the sacrifice layer in the overcoat layer (8); a step of performing sacrifice-layer etching for removing the sacrifice layer using the penetrating hole (10) in order to form a space around the movable portion; and a step of performing a film-formation treatment at a reduced pressure following the sacrifice-layer etching so as to seal the penetrating hole (10).