To provide a discharge valve used for a liquid container such as a bag-in-box or the like, thus allowing easy and accurate connection of piping for transfer of a liquid from the container to a remote place, and easy and prompt discharge of the liquid even from a hermetically closed container or the like.

A discharge valve B used for a liquid container A is composed of a valve main body 1 made of synthetic resin and a valve housing 2 integrally provided a connecting part 21 to a discharge port 3 of the liquid container A with a piping connecting part 23. Depending on the situation, the discharge valve B can be provided with an internal pressure regulating valve disposed within the valve main body 1 for resolving pressure reduction occurring during discharge of liquid from the liquid container A. Alternatively, the valve main body 1 provided with the internal pressure regulating valve and the valve main body 1 having no internal pressure regulating valve may be selectively provided to the valve housing 2 in a detachable and replaceable condition.