A gas supplying device has a plurality of connectors each of which is configured to be connected to a container stored in the corresponding one of supplying storage sections, supply lines configured to divide and supply gas to the plurality of connectors, and a mass flow controller configured to control a flow rate of gas that flows through one of the supply lines. The supply lines include first supply lines each of which is installed to a corresponding supplying storage sections, a second supply line installed upstream of the first supply lines, and a branching supply line for dividing gas supplied from the second supply line into the first supply lines. The mass flow controller is installed in the second supply line and in an installation area.