A counterpressure liquid filling device for a container (1) comprises a gas discharge passage (9a) for discharging the pressurized gas of the container (1) into the atmosphere, the gas discharge passage (9a) being branched into a first branch discharge conduit (12), one end of which is communicated with the neck of the container (1), and a second branch discharge passage (13), one end of which is communicated with the container at a position where the quantity of the liquid to be filled is determined, the other ends of both the first branch discharge conduit (12) and the second branch discharge passage (13) being communicated with a valve operating chamber (11). A gas flow control valve (10) is housed in the valve operating chamber (11). The first branch discharge conduit (12) and the second branch discharge conduit (13) are in communication with mutually opposite sides of the gas flow control valve (10), while the liquid is being filled, but, when the liquid surface has reached the position of quantity determination, the gas flow control valve seals the gas discharge passage (9a). Thus it is possible not only to block the entry of the liquid into the second branch discharge conduit (13), but also to fill the container (1) with the precisely selected quantity of the liquid.