A battery charging system comprising: a heavy electric line adapted to make electrical connection with an external power source; an in-vehicle battery connected electrically with the heavy electric line and arranged to be charged with power supplied through the heavy electric line; a load connected electrically with the heavy electric line and arranged to receive the power supplied through the heavy electric line; a calculating section to calculate a charging power allowable by the battery, as an allowable battery power (P LIM); a battery power requesting section to request supply of charging power to the battery; a load power requesting section to request supply of power to the load; and a controlling section to control supply power to be supplied from the external power source to the battery and the load, in accordance with a request for supply of charging power (P BAT) from the battery power requesting section and a request for supply of load power (P AC) from the load power requesting section, the controlling section being configured to limit power (P SUP) supplied from the external power source to the battery to the allowable battery power (P LIM), and to distribute the supply power (P SUP) from the external power source between the battery and the load when a request for the supply of power to the load is generated by the load power requesting section, characterized in that the controlling section is further configured to hold the limitation of limiting the supply power (P SUP) from the external power source to the allowable battery power (P LIM) after the request for the supply of power to the load is generated by the load power requesting section. a heavy electric line adapted to make electrical connection with an external power source; an in-vehicle battery connected electrically with the heavy electric line and arranged to be charged with power supplied through the heavy electric line; a load connected electrically with the heavy electric line and arranged to receive the power supplied through the heavy electric line; a calculating section to calculate a charging power allowable by the battery, as an allowable battery power (P LIM); a battery power requesting section to request supply of charging power to the battery; a load power requesting section to request supply of power to the load; and a controlling section to control supply power to be supplied from the external power source to the battery and the load, in accordance with a request for supply of charging power (P BAT) from the battery power requesting section and a request for supply of load power (P AC) from the load power requesting section, the controlling section being configured to limit power (P SUP) supplied from the external power source to the battery to the allowable battery power (P LIM), and to distribute the supply power (P SUP) from the external power source between the battery and the load when a request for the supply of power to the load is generated by the load power requesting section, characterized in that the controlling section is further configured to hold the limitation of limiting the supply power (P SUP) from the external power source to the allowable battery power (P LIM) after the request for the supply of power to the load is generated by the load power requesting section.