An apparatus for controlling an engine speed through intermittent control of a driving time and a halt time for an engine-speed adjusting actuator (12) in accordance with the output signal of a difference detecting circuit (6) corresponding to the difference between the outputs of a desired speed computing circuit (5) and an actual speed computing circuit (4). The feature of the invention resides particularly in determining the actuator halt time in proportion to the desired quantity of control for the actuator (12) or the engine operation parameter without limiting the said time to any fixed length, hence eliminating overshoot of the engine speed in the control and ensuring satisfactory apparatus capabilities with a short halt time and enhanced response characteristic.