Abstract: The hydraulic system includes a pump operating unit configured to control the discharge amount of a hydraulic pump by receiving a pilot hydraulic fluid portion from a sensing oil passage. The sensing oil passage includes an operating valve switchable between an open state allowing the sensing oil passage to be open and a closed state blocking the pilot hydraulic fluid portion from flowing toward a control valve in the sensing oil passage The operating valve is maintained in the open state while an operation pressure is less than a setting pressure, the operation pressure being a pressure of the pilot hydraulic fluid portion in a portion of the sensing oil passage between the operating valve and the control valve, and the operating valve is switched to the closed state in response to increasing of the operation pressure to the setting pressure or more.