Abstract: An improved construction of a liquid filler comprised of a filling body, a ball valve, and a mobile lid shutter that executes automated and precise filling operation in a summary structure of having an oil flow control valve and oil exhaustion channel installed on a same filler body for achieving economic and practical benefits by lowering production cost and minimizing failure, and provides safety protection benefits by cutting off flame of any accidental ignition of the oil in the barrel from extending back into the oil tank.