Gas supply system, fuel cell system including gas supply system, and control method for gas supply system

A gas supply system comprising:

• a plurality of tanks that are filled with a gas, the gas filled in the plurality of tanks being compressed;
• a supply pipe that branches and is connected to the plurality of tanks, the supply pipe being configured such that the gas to be supplied to a destination of supply flows through the supply pipe;
• a plurality of shutoff valves that are configured to shut off connections between the plurality of tanks and the supply pipe;
• a plurality of temperature measuring units configured to measure internal temperatures of the plurality of tanks;
• and
• a control unit configured to execute valve opening control for switching the plurality of shutoff valves from a closed state to an open state at a time of start of supply of the gas, the control unit being configured to determine the shutoff valve that is to be opened first out of the plurality of shutoff valves by using the internal temperatures of the plurality of tanks which are measured by the temperature measuring units at the time of start of the supply of the gas in the valve opening control.