PURPOSE: To provide an electronic part mounting structure with a positioning lug made of a shape memory alloy that enables the prevention of contact and short circuits between an electronic part and a circuit board.

CONSTITUTION: An electronic part is formed by placing an electronic device in a case comprising a metal base and a cap. The case has a positioning lug 6 (6a, 6b) formed on its outside, specifically on the surface of the metal base 2 to be opposed to a circuit board 7 on which the electronic part is to be mounted. The positioning lug is made of a unidirectional (or bidirectional) shape memory alloy with the shape of mounting to the circuit board 7 stored therein.