It is an object to provide a method of fabrication for a semiconductor acceleration sensor which can prevent destruction of a movable portion during dicing. A sacrificial layer composed of silicon oxide film is formed on a silicon substrate, and a movable member composed of polycrystalline silicon is formed on the sacrificial layer. A polyimide film is applied on the movable member at room temperature and heated to approximately 350.degree. C. to harden. The movable member is supported by this polyimide film. Accordingly, etching liquid penetration holes are formed on the polyimide film. Further, the sacrificial layer disposed between the movable member and the silicon substrate is etched away by means of dipping the silicon substrate into hydrofluoric acid-based etching liquid. Thereafter, the silicon substrate is dipped into demineralized water to replace the etching liquid with demineralized water, and subsequently the silicon substrate is dried. Accordingly, the silicon substrate is diced and thereafter the polyimide film is etched away by O.sub.2 ashing.