A gas supplying system for fuel cell includes a reformer generating a reformed gas by reforming a mixed raw material including a fuel and a first water, a piping network distributing the reformed gas to fuel cell systems each of which is installed in different rooms or buildings, a drain recovery unit recovering a water condensed from the reformed gas in the piping network. The piping network has a circulating route. By the circulation route, the reformed gas does not stay in the piping network so that the water condensation in the piping is suppressed. The water in the piping is removed by the drain recovery unit. According to this configuration, the clogging and corrosion of the piping caused by the condensed water is avoided.