Abstract: An automatic charging apparatus comprises a rectifier circuit composed of a plurality of diodes and thyristors, said diodes and thyristors being arranged in a bridge connection, a phase control circuit for obtaining the charging voltage of a battery by controlling the phase of said thyristors, a voltage setting resistor for setting a charging voltage suitable for the state of said battery, a current setting resistor for setting a charging current suitable for the state of said battery and a current control circuit which obtains the charging current best suited to the state of the battery by controlling the pulse width of base current flowing in a transistor connected to the outputs of said thyristors. As a result, it is possible to efficiently charge the battery with charging voltage and current best suited to the state of the battery even if the battery is of large capacity.