Patent ID: 7677115

Claim:
A method of manufacturing a rotating shaft, the rotating shaft comprising: a first portion having a first diameter; a second portion being adjacent to the first portion in an axial direction and having a second diameter, wherein the second diameter is smaller than the first diameter; a third portion being adjacent to the second portion in the axial direction in an opposite side of the first portion and having the first diameter; and a magnetostrictive film provided on the second portion, and the method comprising: applying a magnetostrictive material on the second portion, applying a predetermined twist torque by a torque applying apparatus to the rotating shaft in which the magnetostrictive material is applied on the second portion, disposing an induction heating coil on a position facing to the second portion, the induction heating coil including a concave portion having a length substantially equal to a length in an axial direction of the second portion, heating the second portion, in a state in which the predetermined twist torque is applied on the rotating shaft, by the induction heating coil, and releasing the twist torque.