PURPOSE: To form transducer electrodes at minute intervals without using any high-precision mask by applying a holographic exposing method for a photosensitizer.

CONSTITUTION: Metallic films 22B and 23 are formed partially on the reverse surface of piezoelectric material 21, and a metallic film 22 is formed over the entire top surface. The photosensitizer 25 is applied over the surface of the metallic film 22 and then the holographic exposing method is applied for development to form parallel patterns 26 on the photosensitizer 25. Then, the patterns are used as a mask to etch the metallic film 22, forming parallel patterns 27, i.e. a grating pattern on the metallic film 27. Then, a prescribed treatment is carried out to form transducer electrodes. Thus, the transducer electrodes are formed at minute intervals without using any high-precision mask.