For a micromachine having multiple high-power microactuators such as an in-pipe working micromachine, a multiple-microactuator system using a high-frequency pressure source was proposed and developed. The system consists of a high-frequency piezoelectric pressure source, hydraulic microactuator units, and pipes; the hydraulic microactuator unit consists of a bending rubber actuator with two chambers and two thin piezoelectric valves, each of which is connected to the corresponding chamber of the actuator. An alternating flow from the pressure source is rectified by the synchronous switching of the valves, and the bending rubber actuator bends step by step. Each hydraulic microactuator unit needs only one pipe for the supply and return of working fluid, and the small piping space is useful for multiple-actuator systems. In addition, owing to the high-response pressure source and valves, high position resolution and downsizing of the pressure source are realized. A thin piezoelectric valve and a high-frequency piezoelectric pressure source using piezoelectric bimorph disks were proposed, fabricated and experimentally characterized. Then, a 10-mm-long bending rubber actuator was fabricated and a large model system was constructed. Its operation was experimentally tested and characterized, yielding a maximum tip displacement of 3 mm and a maximum force of 12 mN.