To solve a rotation speed defect when a working device and an upper rotating body are simultaneously operated by mounting a switch for operating a control device in a direction for increasing a fuel oil quantity to a rotation operating lever for switching a rotating motor to a normal and reverse rotation state or a stopping state or an operation lever for expanding and shrinking a hydraulic cylinder.

In this construction machine, a pressure oil generated in a hydraulic pump 13 driven by an engine 10 is fed to a working device and a hydraulic cylinder and a rotation motor as a driving source of an upper rotating body. A mechanical governor 14 is provided on the engine 10 and is controlled driving a throttle motor 18 by a controller 22 based on an output signal of a variable resistance switch 26 disposed on a console box 25. In this case, a switch 28 for increasing a fuel amount is attached to an operation lever 27 for controlling the rotating motor and the hydraulic cylinder. In the case where the switch 28 is operated, the operation lever 27 is controlled so as to further increase the engine speed set by the variable resistance switch 26 by a predetermined revolution number.