PURPOSE: To improve the starting performance and to warm an engine subsequently while to maintain lubricant and cooling water at high temperature, by leading combustion gas from a warmer to the environment of an engine corresponding to the temperature at a predetermined position of the engine.

CONSTITUTION: On the basis of the temperature of combustion gas detected through a temperature sensor 47, it is controlled such that when a warmer comprising a combuster 5 and a heatexchanger is operating while an engine 1 is stopping, a changeover valve 25 is closed against an intake tube 3 so as to release a changeover valve 27 arranged in a combustion gas path opened to the atmosphere or a changeover valve 26 arranged in a combustion gas path 90. When the changeover valve 27 is released, combustion gas flows smoothly under this condition because of the function of a blower 31. While when the changeover valve 26 is released, combustion gas is led through the combustion gas path 90 to the outer circumferential face of the engine 1 so as to keep warm the lubricant in case of an oil pan while to keep warm the cooling water in case of a cylinder block.