A non-contact charging system (1, 3) comprising: a power transmission module (i) having a power transmission coil for transmitting high-frequency power; and a power receiving module having a power receiving coil adapted to receive the high-frequency power through electromagnetic induction and a built-in secondary battery charged with DC power obtained by rectifying the received power, the power receiving module including a protection circuit adapted to prevent over-discharge of the secondary battery, wherein the power receiving module includes a switching control section adapted to perform switching between a storage mode where a current path from the secondary battery to all power supply portions including the protection circuit is shut off and a use mode where power supply from the secondary battery is permitted, a loading responsive section that is adapted to output a loading responsive signal when the power receiving module is loaded in a predetermined power receiving position with respect to the power transmission module, and the switching control section is set to maintain the storage mode in an initial state, and configured to switch the mode to the use mode and maintain the mode in response to output of the loading responsive signal, characterized by comprising an operation limiting section that limits the operation of the switching control section according to a carrier time width that is a time width over which the power receiving carrier of the high-frequency power is present in the output of the power receiving coil, wherein the operation limiting section performs control to permit switching to the use mode by the switching control section when the carrier time width exceeds a fixed length. a power transmission module (i) having a power transmission coil for transmitting high-frequency power; and a power receiving module having a power receiving coil adapted to receive the high-frequency power through electromagnetic induction and a built-in secondary battery charged with DC power obtained by rectifying the received power, the power receiving module including a protection circuit adapted to prevent over-discharge of the secondary battery, wherein the power receiving module includes a switching control section adapted to perform switching between a storage mode where a current path from the secondary battery to all power supply portions including the protection circuit is shut off and a use mode where power supply from the secondary battery is permitted, a loading responsive section that is adapted to output a loading responsive signal when the power receiving module is loaded in a predetermined power receiving position with respect to the power transmission module, and a switching control section adapted to perform switching between a storage mode where a current path from the secondary battery to all power supply portions including the protection circuit is shut off and a use mode where power supply from the secondary battery is permitted, a loading responsive section that is adapted to output a loading responsive signal when the power receiving module is loaded in a predetermined power receiving position with respect to the power transmission module, and the switching control section is set to maintain the storage mode in an initial state, and configured to switch the mode to the use mode and maintain the mode in response to output of the loading responsive signal, characterized by comprising an operation limiting section that limits the operation of the switching control section according to a carrier time width that is a time width over which the power receiving carrier of the high-frequency power is present in the output of the power receiving coil, wherein the operation limiting section performs control to permit switching to the use mode by the switching control section when the carrier time width exceeds a fixed length.