PURPOSE: To permit the reasonable and speedy warming by carrying out warming by utilizing the exhaust brake on the basis of the engine cooling water temperature.

CONSTITUTION: The water temperature (t) of a water temperature sensor 14 on the engine start and a set value t1 are compared, and when t≤t1, and no clutch or accelerator pedal is stepped ON, if t≤t2 for t2(>t1), a solenoid valve 6 is operated, and an exhaust brake is operated. At the same time, the number of engine revolution is set to a set value N1. If t1≤t≤t2, the exhaust brake is not operated, and the number of engine revolution is set to a set value N2(>N1). When the pedal is stepped ON and t>t2, the exhaust brake is released, and the number of engine revolution is set to N2. If t>t2, the exhaust brake is not operated, and the number of engine revolution is set to a value N3(<N1). Warming proceeds, and if t>t2, the exhaust brake is released, and the number of engine revolution is set to the set value N3. Thus warming can be accelerat ed, and the generation of white smoke can be reduced.