To provide a noncontact charging battery system in which a secondary battery requiring control of the charging voltage can be charged easily.

The noncontact charging battery system comprises a battery pack 2 for storing a secondary battery, and a charger 1 for supplying the secondary battery with charging energy. The charger 1 includes a section 10 for outputting the charging energy as electromagnetic energy, and a charger side control section 14 for controlling operation of the electromagnetic energy output section 10, and the battery pack 2 includes a reconverting section 20 for converting inputted electromagnetic energy into DC power, and a battery pack side control section 23 for controlling at least the voltage of DC power.