PURPOSE: To enhance the reliability of wire bonding and to improve the yield by making a close contact part of a connection part in a piezoelectric substrate to be a rough face for strengthening the close contact force.

CONSTITUTION: The element consists of a piezoelectric substrate 1, an electromechanical transducer (electrode) 2, a mechanoelectrical transducer (electrode) 3, connection parts 4, 5, wire members 6, 7 and a rough face R. Then the rough face R of the piezoelectric substrate 1 holds the connection parts 4, 5 patterned thereon with a large contact area so that the connection parts 4, 5 are not easily exfoliated. Thus, even when the film thickness of the connection parts 4, 5 is thin, a sufficient close adhesion force of the connection parts 4, 5 onto the piezoelectric substrate 1 is ensured regardless wire bond of wire members 6, 7 to the connection parts 4, 5. Thus, the reliability of wire bond connection is enhanced and the yield is improved.