Provided is construction machinery that is capable of greatly reducing the amount of fuel consumption by making effective use of recovered energy. The construction machinery has a first hydraulic pump 3 for discharging hydraulic oil for driving an actuator 6, a second hydraulic pump 9, a second prime mover 7 for driving the second hydraulic pump 9, energy storage device 8 for storing energy for driving the second prime mover 7, and a hydraulic oil supply circuit 10 including a hydraulic oil switching section 11c that accepts the hydraulic oil discharged from the first hydraulic pump and the hydraulic oil discharged from the second hydraulic pump and supplies either the mixture of the accepted hydraulic oils or a selected one of the accepted hydraulic oils to the actuator 6. The construction machinery includes a control device 20 that, when the drive efficiency of the second hydraulic pump 9 and/or the amount of energy stored in the energy storage device 8 is higher than a preselected setting value, outputs a switch command to the hydraulic oil switching section 11c and outputs a drive command to the second prime mover 7.