A photothermal actuator comprises an optical fiber bundle, a light inputting apparatus, and a thermal receiving element. The optical fiber bundle is inserted in a tube of a catheter etc. The light inputting apparatus inputs light into the optical fiber bundle. The thermal receiving element is provided on a part of an outer surface of the optical fiber bundle. The thermal receiving element is heated by the light so that the thermal receiving element and a part of the optical fiber bundle are stretched, whereby the optical fiber bundle and the tube are bent.