In order to provide a catheter which can be operated even when it is deformed inside a bent blood vessel and whose movable part can be easily bent and the movable part thus bent is firmly kept in this shape, a catheter includes: a fluid-driven actuator including: a balloon a restricting member for restricting inflation of the balloon in a short axis direction of the catheter and a tube which is less stretchable in a long axis direction of the catheter than the balloon is, according to a cross-sectional view of the fluid-driven actuator taken along the short axis direction of the catheter, the tube being eccentrically provided with respect to the restricting member.
