A deceleration control apparatus is provided which can control a two-cycle engine of the spark ignition type for a vehicle, in which fresh air in a combustion chamber can be self-ignited at an ignition timing preferable for operation of the engine at least upon low load operation, so that, when engine sudden deceleration requirements are satisfied, the combustion condition is automatically changed over from an activated heat atmosphere combustion condition to an ordinary combustion condition to allow sudden deceleration of the engine. A sudden deceleration requirement discrimination CPU for discriminating requirements which require sudden deceleration of the vehicle receives, in addition to a detection signal from a throttle valve opening sensor, detection signals from a vehicle speed sensor, a kill switch, a main switch, a brake switch for detecting that the brakes are applied, a clutch switch for detecting that the clutch is disconnected, and a gear position switch for detecting that the shift operation position is operated to the neutral position, and when the requirements which require sudden deceleration are satisfied, the sudden deceleration requirement discrimination CPU sends an exhaust control valve opening correction signal to an exhaust control valve CPU.