To provide a hydraulic circuit capable of repairing, inspecting and maintaining a sandwich valve, capable of repairing, inspecting and maintaining hydraulic equipment, and capable of flushing a circuit at the same time while driving a hydraulic pressure source.

A hydraulic pressure source and a sandwich valve, flushing, and hydraulic equipment can be repaired, inspected and maintained concurrently by constitution interposed with a composite valve 30 between the sandwich valve 20 and a multifunctional valve 40 connected to the hydraulic pressure source 10 and the hydraulic equipment 60, in a hydraulic circuit, and provided, in the composite valve, with a stop valve of conducting opening and closing between the hydraulic pressure source and the sandwich valve and between the sandwich valve and the multifunctional valve, a stop valve of conducting opening and closing between the hydraulic pressure source and the multifunctional valve, and bypass circuits 35b, 36b provided with stop valves 35a, 36a of conducting opening and closing between the hydraulic pressure source and the multifunctional valve, in a hydraulic pressure source side of the stop valves, and also a hydraulic cylinder 61 can be trial-runned thereby. Further the composite valve is easy to be manufactured by standardizing circuit constitution thereof.