To improve exhaust emission of a hybrid vehicle having an internal combustion engine and an auxiliary power supply by storing heat generated by the internal combustion engine during the operation of the internal combustion engine, and using the stored heat when the internal combustion engine is stopped to restrain a temperature drop of an exhaust emission purifying catalyst.

A regenerative exhaust emission purifying mechanism 14 for purifying toxic gas component in exhaust emission is disposed in the midway of an exhaust pide 13 in an internal combustion engine. During the operation of the internal combustion engine, heat of exhaust emission passing through an inner cylinder 140 of the regenerative exhaust emission purifying mechanism 14 is stored in a heat storing material 143 disposed in the peripheral wall of the inner cylinder 140. When the internal combustion engine is stopped, radiation of heat of the exhaust emission purifying catalyst 142 and the heat storing material 143 disposed in the inner cylinder 140 is intercepted by a vacuum heat insulation layer 144 disposed between the inner cylinder 140 and an outer cylinder 141, and heat stored in the heat storing material 143 is transmitted to the exhaust emission purifying catalyst, thereby restraining a temperature drop. Thus, exhaust emission at the restarting of the internal combustion engine is improved.