A construction machine capable of increasing a frictional force and an acceleration performance without causing unwanted slip and an excessive load to a transmission by a driving force. The construction machine comprises a first mode to set the maximum output of an engine to a prescribed output, a second mode to limit the maximum output of the engine to an output lower than the prescribed output and a mode selector switch used for a operator to select from the plurality of modes. The construction machine also comprises control means that controls the machine to operate in the second mode regardless of the mode selected by the mode selector switch when a vehicle speed is equal to or less than a prescribed speed and the opening of an accelerator is equal to or more than a prescribed opening.