A construction machine capable of notifying an operator or the like of an energy saving state such that an engine thereof stops irrespective of the operator's will. The construction machine, wherein its engine is controlled to be in an energy saving state when an operator leaves from an operator's seat and no work is performed, includes various display devices for displaying the energy saving state. The various display devices include a display lamp that is capable of being recognized from the outside of the machine, and a monitor screen that is provided in an operator's cabin as a monitor display.