To reduce a catalyst warming-up time at a start of an engine using a simple device in a plug-in hybrid vehicle.

A catalyst warming-up device for warming up a purification catalyst 14 of the plug-in hybrid vehicle 100 provided with a plurality of power sources including the engine, the purification catalyst 14 for purifying exhaust gas exhausted from the engine, and a charger 12 which can be charged from an external power source includes a radiator plate 16 which conducts waste heat generated by the charger 12 to radiate it to the purification catalyst 14 as a radiation heat.