The stiffness variable device (10) includes a first longitudinal member (30), a second longitudinal member (40), and an inducer (50). The first longitudinal member (30) has at least one high bending stiffness portion (31) and at least one low bending stiffness portion (33). The induction body (50) is arranged around the low bending rigidity portion (33), and the first phase and the second phase are arranged in one part of the shape memory member (41) of the second longitudinal member (40). The phase change of the shape memory member (41) is caused to change the rigidity of one part of the second longitudinal member (40) in the longitudinal axis direction of the second longitudinal member (40).剛性可変装置（１０）は、第１の長手部材（３０）と第２の長手部材（４０）と誘起体（５０）とを有する。第１の長手部材（３０）は、少なくとも１つの高曲げ剛性部（３１）と少なくとも１つの低曲げ剛性部（３３）とを有する。誘起体（５０）は、低曲げ剛性部（３３）の周辺に配置される、第２の長手部材（４０）の形状記憶部材（４１）の一部位において、第１の相と第２の相との間で形状記憶部材（４１）の前記相の移り変わりを引き起こさせて、第２の長手部材（４０）の長手軸方向における第２の長手部材（４０）の一部位の剛性を変更させる。
