A first target engine speed is set in response to a command value commanded by a command unit. A second target engine speed equal to or lower than the first target engine speed is set based on the first target engine speed. When the first target engine speed is reduced, the second target engine speed is set to be constant or be decreased and a reduction range for decreasing the first target engine speed to the second target engine speed is set to be decreased. The reduction range is set at zero when the first target engine speed is equal to or lower than an engine speed at least at a maximum torque point.