A variable stiffness actuator includes a shape-memory member, and a heater configured to receive power to heat the shape-memory member so as to cause the shape-memory member to change from a first phase as a low stiffness state to a second phase as a high stiffness state showing a higher stiffness than the low stiffness state. The actuator also includes a first conductive wire having one end connected to the heater and constituting a part of a power supply line for the heater, and a second conductive wire having one end connected to the other end of the first conductive wire, thicker than the first conductive wire, and having an electrical resistance per unit length lower than that of the first conductive wire.
