To provide a construction machine in which energy efficiency in a hydraulic pump is improved.

The construction machine includes: a hydraulic pump driven by a motor; a hydraulic actuator for hydraulically driving a working element; a control valve controlling a pressure oil flow from the hydraulic pump to the hydraulic actuator; a continuously variable transmission arranged between the motor and the hydraulic pump; an engine speed detecting means detecting an engine speed of the motor; a pump speed calculation means calculating a speed of the hydraulic pump; and a reduction ratio control means controlling a reduction ratio of the continuously variable transmission based on the engine speed detected by the engine speed detecting means and the speed calculated by the pump speed calculation means.