A construction machine comprising: a driven body configured to rotate about a horizontal axis in a raising direction and a lowering direction; a hydraulic cylinder that rotates and drives the driven body; a plurality of switching valves (15A, 15B) that is connected to, among a rod-side chamber and a head-side chamber of the hydraulic cylinder, a discharge-side chamber from which hydraulic oil is discharged during rotation of the driven body in the lowering direction, and that is configured to switch between a discharge state in which the discharge of the hydraulic oil from the discharge-side chamber is allowed and a stopped state in which the discharge of the hydraulic oil is stopped; an operating unit configured to switch the plurality of switching valves (15A, 15B) from the stopped state to the discharge state; a plurality of lock valves (16A, 16B) each provided between each of the plurality of switching valves (15A, 15B) and the discharge-side chamber in order to lock the rotation of the driven body in the lowering direction in a non-operating state of the operating unit; and an operation control unit that controls the operation of the plurality of lock valves (16A, 16B), wherein each of the plurality of lock valves (16A, 16B) includes a valve element configured to move between a locking position at which the discharge of the hydraulic oil from the discharge-side chamber is restricted and an unlocking position at which the discharge of the hydraulic oil from the discharge-side chamber is allowed, characterized in that the operation control unit controls the operation of the plurality of lock valves (16A, 16B) so that the plurality of valve elements moves from the locking position to the unlocking position at different points in time when the operating unit is operated. a driven body configured to rotate about a horizontal axis in a raising direction and a lowering direction; a hydraulic cylinder that rotates and drives the driven body; a plurality of switching valves (15A, 15B) that is connected to, among a rod-side chamber and a head-side chamber of the hydraulic cylinder, a discharge-side chamber from which hydraulic oil is discharged during rotation of the driven body in the lowering direction, and that is configured to switch between a discharge state in which the discharge of the hydraulic oil from the discharge-side chamber is allowed and a stopped state in which the discharge of the hydraulic oil is stopped; an operating unit configured to switch the plurality of switching valves (15A, 15B) from the stopped state to the discharge state; a plurality of lock valves (16A, 16B) each provided between each of the plurality of switching valves (15A, 15B) and the discharge-side chamber in order to lock the rotation of the driven body in the lowering direction in a non-operating state of the operating unit; and an operation control unit that controls the operation of the plurality of lock valves (16A, 16B), wherein each of the plurality of lock valves (16A, 16B) includes a valve element configured to move between a locking position at which the discharge of the hydraulic oil from the discharge-side chamber is restricted and an unlocking position at which the discharge of the hydraulic oil from the discharge-side chamber is allowed, characterized in that the operation control unit controls the operation of the plurality of lock valves (16A, 16B) so that the plurality of valve elements moves from the locking position to the unlocking position at different points in time when the operating unit is operated.