An object of the present invention is to provide a construction machine that has a hydraulic closed-circuit system mounted therein and capable of selectively connecting some of a plurality of hydraulic pumps driven by two engines to any one of a plurality of hydraulic actuators and that can downsize the engines while maintaining high work efficiency. A controller 80 includes an actuator/engine allocation computing section F6 that, at the time of connecting closed-circuit pumps that are not connected to any of the hydraulic actuators 1, 3, 5, and 7 to any one of the hydraulic actuators, allocates closed-circuit pumps driven by a right engine 9b to the one hydraulic actuator in a case in which an estimated maximum load on a left engine 9a is heavier than an estimated maximum load on the right engine, and allocates closed-circuit pumps driven by the left engine to the one hydraulic actuator in a case in which the estimated maximum load on the right engine is heavier than the estimated maximum load on the left engine.