A variable stiffness apparatus to be installed in a flexible member includes a first elongated member, a second elongated member arranged along the first elongated member, and an inducing member. The first elongated member includes a high bending stiffness portion, and a low bending stiffness portion. The second elongated member includes a shape-memory member that takes a low-stiffness state when in a first phase and a high-stiffness state when in a second phase. The inducing member causes a region of the shape memory member that is arranged around the low bending stiffness portion to transition in phase between the first phase and the second phase, so as to change the stiffness of the region of the second elongated member.
