A construction machine, comprising: a hydraulic actuator drivable by hydraulic fluid delivered from a hydraulic pump; a control valve for controlling supply and discharge of hydraulic fluid to and from the hydraulic actuator according to a position of a spool thereof; an operation device for controlling a position of a spool of the control valve according to an operation amount and an operation direction; a load sensor (41, 42) for detecting a magnitude of a negative load applied by an external force to the hydraulic actuator in a same direction as an actuation direction of the hydraulic actuator; a first flow passage through which hydraulic fluid discharged from the hydraulic actuator flows when the hydraulic actuator is actuated in the same direction as the negative load, the first flow passage passing through the control valve; a first variable restrictor (22a, 22b, 23a, 23b) provided in the control valve in the first flow passage; and a control device (45, 45A, 45B) for reducing the opening area of the first variable restrictor by changing the position of the spool of the control valve according to the increase in the magnitude of the negative load detected by the load sensor (41, 42); characterized in that a range in which the opening area of the first variable restrictor is varied by the control device (45, 45A, 45B) according to the increase in the magnitude of the negative load detected by the load sensor (41, 42) has an upper limit value and a lower limit value with respect to each value of the operation amount of the operation device; and the upper limit value and the lower limit value are increased according to the increase in the operation amount of the operation device. a hydraulic actuator drivable by hydraulic fluid delivered from a hydraulic pump; a control valve for controlling supply and discharge of hydraulic fluid to and from the hydraulic actuator according to a position of a spool thereof; an operation device for controlling a position of a spool of the control valve according to an operation amount and an operation direction; a load sensor (41, 42) for detecting a magnitude of a negative load applied by an external force to the hydraulic actuator in a same direction as an actuation direction of the hydraulic actuator; a first flow passage through which hydraulic fluid discharged from the hydraulic actuator flows when the hydraulic actuator is actuated in the same direction as the negative load, the first flow passage passing through the control valve; a first variable restrictor (22a, 22b, 23a, 23b) provided in the control valve in the first flow passage; and a control device (45, 45A, 45B) for reducing the opening area of the first variable restrictor by changing the position of the spool of the control valve according to the increase in the magnitude of the negative load detected by the load sensor (41, 42); characterized in that a range in which the opening area of the first variable restrictor is varied by the control device (45, 45A, 45B) according to the increase in the magnitude of the negative load detected by the load sensor (41, 42) has an upper limit value and a lower limit value with respect to each value of the operation amount of the operation device; and the upper limit value and the lower limit value are increased according to the increase in the operation amount of the operation device.