Work machine

A work machine comprising:

• a pump that delivers a hydraulic fluid sucked from a tank;
• a hydraulic actuator that is driven by the hydraulic fluid delivered from the pump;
• a flow control valve having a center bypass passage section that introduces the hydraulic fluid from the pump into the tank when the flow control valve is in a neutral position and controlling a flow rate of the hydraulic fluid supplied to the hydraulic actuator according to an amount of displacement thereof from the neutral position;
• a center bypass line that introduces the hydraulic fluid supplied from the pump through the center bypass passage section of the flow control valve into the tank;
• a bypass cutoff valve that is provided downstream of the flow control valve in the center bypass line and that controls an opening of the center bypass line;
• a solenoid proportional valve that generates a pilot pressure for controlling the bypass cutoff valve;
• an operation device that operates the hydraulic actuator;
• a pilot valve that generates a pilot pressure for controlling the flow control valve on a basis of an amount of operation of the operation device;
• an amount-of-operation sensor that senses the amount of operation of the operation device;
• and
• a controller that controls the solenoid proportional valve on a basis of the amount of operation sensed by the amount-of-operation sensor,
• wherein the controller controls the solenoid proportional valve to reduce an opening area of the bypass cutoff valve to a minimum opening area according to an increase in the amount of operation in a case the amount of operation sensed by the amount-of-operation sensor is in a range from a minimum amount of operation to less than a predetermined amount of operation, and
• the controller controls the solenoid proportional valve to make the opening area of the bypass cutoff valve larger than the minimum opening area in a case the amount of operation sensed by the amount-of-operation sensor is a maximum amount of operation.