When the mobile type information terminal is transferred between an operating state and a standby state, self diagnosis is performed. The fuel cell charges the secondary cells with a normal current of fixed value I1, and when the output voltage of the boost DC/DC converter (when PG=L), the charge current is reduced to the fixed value and aging is performed. After aging is performed for 60 seconds, charging is performed once again performed at the normal fixed value I1. This type of operation is repeated 30 times. During aging, when the output voltage from the boost DC/DC converter is reduced (when PG=L), aging is stopped and after 20 seconds aging is performed again, and this operation is done 10 times. The mobile type information terminal can perform self diagnosis and retrial of regeneration without the user being aware, in which secondary batteries and a fuel cell are loaded.