An object is to take measures to reduce engine exhaust gas of an externally chargeable electric/hybrid vehicle. An externally chargeable electric/hybrid vehicle comprises a battery for supplying electrical power to the motor, a generator that charges the battery with electrical power generated by the driving forces of the engine, and an external charging unit that supplies electrical power from an external power supply device to the battery to charge the battery, and the vehicle travels in either an EV mode or an HV mode. The vehicle further comprises a charged amount measuring unit for measuring externally charged electrical energy supplied from the external charging unit to the battery, and a travel mode determination unit for determining in which driving mode of the EV mode or the HV mode the vehicle travels, based on the externally charged electrical energy. The vehicle travels in a travel mode according to the result determined by the travel mode determination unit.