To easily increase action speed in shape memory wire without generating noise.

Shape memory wire 1 characterized by fixing heat radiation members 5 having greater heat capacity than shape memory alloy on a wire main body 3 of wire made out of the shape memory alloy is provided. A plurality of the heat radiation members 5 is arranged with making a line in a longitudinal direction of the wire main body 3 with keeping an interval. Heat capacity of the heat radiation members 5 is greater than heat capacity of the wire main body 3 arranged between the heat radiation members mutually adjoining.