To provide an easily breakable fastening part having sufficient fastening force even in a martensitic phase.

This easily breakable corresponding fastening part couples, unites and holds a plurality of parts, members and equipment, has the fastening function at a normal use time and loses the fastening function by heating. The fastening part is made of a shape memory alloy member and a spring member. The fastening function is strengthened or imparted by using constraint force by the spring member at the normal use time. When heating the fastening part, constraining of the spring member by the shape memory alloy member is released and the fastening function can be lost.