PURPOSE: To provide high reliability and facilitate the miniaturization by erecting a plurality of cylindrical elastic bodies on a plurality of surfaces of a base with the prescribed arrangement, and communicating at least two pressure chambers of the respective cylindrical elastic bodies with different flow passages.

CONSTITUTION: Three bulkheads 105, 106, 107 are formed at an interval of approximately 120° in a flexible actuator (cylindrical elastic body) 108. When the pressure in a pressure chamber 114 is increased by feeding the working fluid from a tube 111a, the pressure chamber 114 is expanded in the axial direction, and the cylindrical elastic body 108 is curved in the A direction to show the condition by the chain line. When the pressure in a pressure chamber 116 is further increased in this condition through a tube 111c, the cylindrical elastic body 108 is curved in the C direction away from the plan. The cylindrical elastic body 108 is curved in an arbitrary direction by combining the pressures to be given to three pressure chambers 114, 115, 116. This constitution moves the flexible actuator 108.