A hybrid vehicle 1 includes as drive sources an internal combustion engine 20, to which fuel stored in a fuel tank 21 is supplied, and a second M/G 32, to which electricity stored in a battery 40 is supplied. The vehicle 1 also includes a battery charger 70 for charging the battery 40 from the outside of the vehicle 1. For each of a plurality of refuelings to the fuel tank 21, the history of the time of refueling and the amount of refueling are stored. Based on the history, the degree of deterioration of fuel in the fuel tank 21 is calculated.