A construction machine comprising: a power source (1, 6); a plurality of actuators (13, 23, 33, 43) that operate by receiving a power from the power source (1, 6); a plurality of control levers (14, 34) that instruct amounts of the power to be distributed to the plurality of actuators (13, 23, 33, 43); a plurality of operation state sensors (17r, 17b, 274, 27b, 37r, 37b, 47r, 471) that detect operation states of the plurality of control levers (14, 34); and a controller that controls the power output by the power source (1, 6), the controller being configured to perform power reduction control of the power source (1, 6) on a basis of the operation states of the plurality of control levers (14, 34) detected by the plurality of operation state sensors (17r, 17b, 274, 27b, 37r, 37b, 47r, 471) when a non-operation time of the plurality of control levers (14, 34) exceeds a set time after a transition is made from a state in which at least one of the plurality of control levers (14, 34) is operated to a non-operation state in which none of the plurality of control levers (14, 34) is operated, and to cancel the power reduction control when at least one of the plurality of control levers (14, 34) is operated in a state in which the power reduction control is performed, characterised in that the controller is further configured to set the set time as a first set time when an operation time until the at least one control lever makes a transition to the non-operation state is longer than a monitoring time set in advance, and set the set time as a second set time shorter than the first set time when the operation time until the at least one control lever makes a transition to the non-operation state is shorter than the monitoring time set in advance. a power source (1, 6); a plurality of actuators (13, 23, 33, 43) that operate by receiving a power from the power source (1, 6); a plurality of control levers (14, 34) that instruct amounts of the power to be distributed to the plurality of actuators (13, 23, 33, 43); a plurality of operation state sensors (17r, 17b, 274, 27b, 37r, 37b, 47r, 471) that detect operation states of the plurality of control levers (14, 34); and a controller that controls the power output by the power source (1, 6), the controller being configured to perform power reduction control of the power source (1, 6) on a basis of the operation states of the plurality of control levers (14, 34) detected by the plurality of operation state sensors (17r, 17b, 274, 27b, 37r, 37b, 47r, 471) when a non-operation time of the plurality of control levers (14, 34) exceeds a set time after a transition is made from a state in which at least one of the plurality of control levers (14, 34) is operated to a non-operation state in which none of the plurality of control levers (14, 34) is operated, and to cancel the power reduction control when at least one of the plurality of control levers (14, 34) is operated in a state in which the power reduction control is performed, characterised in that the controller is further configured to set the set time as a first set time when an operation time until the at least one control lever makes a transition to the non-operation state is longer than a monitoring time set in advance, and set the set time as a second set time shorter than the first set time when the operation time until the at least one control lever makes a transition to the non-operation state is shorter than the monitoring time set in advance.