Abstract: A battery-charging circuit capable of promptly detecting, during quick charging, an abnormality of a secondary battery of a battery, if any, and making it impossible to continue the quick charge thereafter. As a battery-charging circuit for quickly charging a secondary battery with a predetermined charging current from a battery-charging power source having a constant-characteristic, the battery charging circuit includes a voltage-measuring device for measuring the secondary battery voltage at predetermined regular time intervals; a voltage-setting device for presetting a reference voltage value at a level higher, by a predetermined magnitude, than an expected charge complete voltage value; a comparator device for comparing with the preset reference voltage value a battery voltage actually measured during the quick charge operation; and a current limiter circuit for stopping the quick charge when the battery voltage has risen to the reference voltage value.