In a hybrid vehicle of the invention, when a voltage level E of a low-voltage battery exceeds a preset alert reference value Eth1 (step S115), fueling control activates a negative pressure pump with a preset amount of power consumption for standard fuel vapor treatment (step S125). When the voltage level E of the low-voltage battery exceeds a low charge reference value Elow but is not higher than the preset alert reference value Eth1 (steps S115 and S120), the fueling control activates the negative pressure pump with a smaller amount of power consumption (step S130). When the voltage level E of the low-voltage battery is not higher than the low charge reference value Elow (step S120), the fueling control inactivates the negative pressure pump (step S135). Such control enables at least a voltage of the low charge reference value Elow to be reserved in the low-voltage battery even after regulation of internal pressure of a fuel tank. This effectively prevents an insufficiency of electrical energy by the regulation of the internal pressure of the fuel tank.