A hydrogen gas dissolving apparatus comprising a hydrogen supply unit capable of supplying hydrogen gas, and a hydrogen gas dissolution module for making the hydrogen gas supplied from the hydrogen supply unit being contact with and dissolved in water, wherein the hydrogen gas dissolution module comprises a supply port to which the hydrogen gas can be supplied, a hydrogen chamber communicating with the supply port whcih can be filled with the hydrogen gas supplied from the supply port, and an exhaust port communicating with the hydrogen chamber, the exhaust port being for discharging air which fills the hydrogen chamber before the hydrogen gas is supplied from the supply port, and the exhaust port is located in a lower part of the hydrogen chamber, and below the exhaust port, an open/close valve controlled by a control unit is provided, characterized in that the control unit is configured to control the open/close valve such that in an initial state before a start of operation of the hydrogen gas dissolving apparatus, the control unit lets the open/close valve opened, whereby, when the hydrogen supply unit starts to supply the hydrogen gas so that the hydrogen gas dissolution module starts to produce hydrogen water, the air in the hydrogen chamber is moved down by the supplied hydrogen gas and discharged through the exhaust port and the opened open/close valve, and when the amount of the hydrogen gas supplied to the hydrogen chamber exceeds the internal volume of the hydrogen chamber, the control unit determines that the air is completely discharged from the hydrogen chamber, and the control unit closes the open/close valve, wherein after the open/close valve is closed by the control unit, the hydrogen supply unit continues to supply the hydrogen gas to pressurize the inside of the hydrogen chamber. the hydrogen gas dissolution module comprises a supply port to which the hydrogen gas can be supplied, a hydrogen chamber communicating with the supply port whcih can be filled with the hydrogen gas supplied from the supply port, and an exhaust port communicating with the hydrogen chamber, the exhaust port being for discharging air which fills the hydrogen chamber before the hydrogen gas is supplied from the supply port, and the exhaust port is located in a lower part of the hydrogen chamber, and below the exhaust port, an open/close valve controlled by a control unit is provided, characterized in that the control unit is configured to control the open/close valve such that in an initial state before a start of operation of the hydrogen gas dissolving apparatus, the control unit lets the open/close valve opened, whereby, when the hydrogen supply unit starts to supply the hydrogen gas so that the hydrogen gas dissolution module starts to produce hydrogen water, the air in the hydrogen chamber is moved down by the supplied hydrogen gas and discharged through the exhaust port and the opened open/close valve, and when the amount of the hydrogen gas supplied to the hydrogen chamber exceeds the internal volume of the hydrogen chamber, the control unit determines that the air is completely discharged from the hydrogen chamber, and the control unit closes the open/close valve, wherein after the open/close valve is closed by the control unit, the hydrogen supply unit continues to supply the hydrogen gas to pressurize the inside of the hydrogen chamber.