To provide a hydrogen gas replenishment control system that maintains a constant temperature of hydrogen gas to be replenished and efficiently supplies hydrogen gas to a hydrogen-cooled generator.

A hydrogen gas replenishment control system includes: a hydrogen gas transfer pipe 2 that is provide between an upstream gas cylinder chamber 20 and a downstream turbine building 10, and sends a hydrogen gas released from a hydrogen gas cylinder 6; a barometer 11 that measures a pressure of the hydrogen gas in the turbine generator 1; a thermometer 7 that measures a temperature of the hydrogen gas immediately before leading to the barometer 11; and a temperature controller 8 that control a temperature so that a temperature of the hydrogen gas measured by the thermometer 7 in the hydrogen gas transfer pipe 2 falls in a predetermined temperature range.