A hydraulic circuit having a holding valve of an external pilot pressure operation type is provided, which can make a double check valve (6), which is installed to prevent an actuator (1) from being pushed due to leakage of hydraulic fluid of a main control valve (2), be opened by an external signal pressure being supplied to shift the main control valve (2). The hydraulic circuit includes a hydraulic pump (P) connected to an engine and a pilot pump (Pp), a hydraulic cylinder (1) connected to the hydraulic pump (P) to expand and contract when hydraulic fluid is supplied thereto, a main control valve (2) installed in a flow path between the hydraulic pump (P) and the hydraulic cylinder (1) and shifted to control a start, a stop, and a direction change of the hydraulic cylinder (1), a joystick (11) outputting a pilot signal pressure from the pilot pump (Pp) in accordance with an amount of user's manipulation thereof, a double check valve (6) installed in a flow path between the main control valve (2) and the hy
