A bending joint mechanism includes a joint section (3, 194). The joint section (3, 194) includes a shaft section (2, 192), an actuating section (6, 196), a coupling member (7, 206) and a rod section (13, 205). The rod section (13, 205) has an elastic portion (16, 205) which is elastically deformable in directions other than the axial direction of the shaft section (2, 192).