A gas supply device, comprising: a supply path that is used to supply vaporized gas, obtained as a result of liquefied gas in a tank being vaporized by a heat exchanger, to a supply destination, whereby the supply path extends from the tank and is connected to a gas consumption equipment; and a reflux path that is used to reflux vaporized gas, obtained as a result of the liquefied gas in the tank being vaporized, to the tank; wherein: pressure adjustment means provided in the reflux path adjusts an inner pressure of the tank, so that gas is supplied via the supply path; the tank includes a vacuum heat-insulating layer, and an outer wall and an inner wall that sandwich the vacuum heat-insulating layer; a liquefied gas storage section that stores the liquefied gas is provided inside the inner wall; an inner heat-blocking chamber that vaporizes the liquefied gas is provided, which is surrounded by the vacuum heat-insulating layer and in the inner heat-blocking chamber, a heat exchange section that heats and vaporizes the liquefied gas introduced thereinto is provided; a guide-out path, through which the liquefied gas is guided out from the liquefied gas storage section to the inner heat-blocking chamber, is formed between the liquefied gas storage section and the inner heat-blocking chamber; the supply path is connected to the liquefied gas storage section, characterized in that an end of the reflux path is connected to a gas phase space in the liquefied gas storage section that is above the liquefied gas, whereby the supply path and the reflux path are independent from each other; an outlet through which the vaporized gas flows out to the reflux path is formed in a top part of the inner heat-blocking chamber; and used as a heating medium for the heat exchange section is the gas that circulates in a heating medium circulation path that extends from the inside to the outside of the tank to circulate gas, a part thereof that is located inside the tank being the heat exchange section. a supply path that is used to supply vaporized gas, obtained as a result of liquefied gas in a tank being vaporized by a heat exchanger, to a supply destination, whereby the supply path extends from the tank and is connected to a gas consumption equipment; and a reflux path that is used to reflux vaporized gas, obtained as a result of the liquefied gas in the tank being vaporized, to the tank; wherein: pressure adjustment means provided in the reflux path adjusts an inner pressure of the tank, so that gas is supplied via the supply path; the tank includes a vacuum heat-insulating layer, and an outer wall and an inner wall that sandwich the vacuum heat-insulating layer; a liquefied gas storage section that stores the liquefied gas is provided inside the inner wall; an inner heat-blocking chamber that vaporizes the liquefied gas is provided, which is surrounded by the vacuum heat-insulating layer and in the inner heat-blocking chamber, a heat exchange section that heats and vaporizes the liquefied gas introduced thereinto is provided; a guide-out path, through which the liquefied gas is guided out from the liquefied gas storage section to the inner heat-blocking chamber, is formed between the liquefied gas storage section and the inner heat-blocking chamber; the supply path is connected to the liquefied gas storage section, characterized in that an end of the reflux path is connected to a gas phase space in the liquefied gas storage section that is above the liquefied gas, whereby the supply path and the reflux path are independent from each other; an outlet through which the vaporized gas flows out to the reflux path is formed in a top part of the inner heat-blocking chamber; and used as a heating medium for the heat exchange section is the gas that circulates in a heating medium circulation path that extends from the inside to the outside of the tank to circulate gas, a part thereof that is located inside the tank being the heat exchange section. pressure adjustment means provided in the reflux path adjusts an inner pressure of the tank, so that gas is supplied via the supply path; the tank includes a vacuum heat-insulating layer, and an outer wall and an inner wall that sandwich the vacuum heat-insulating layer; a liquefied gas storage section that stores the liquefied gas is provided inside the inner wall; an inner heat-blocking chamber that vaporizes the liquefied gas is provided, which is surrounded by the vacuum heat-insulating layer and in the inner heat-blocking chamber, a heat exchange section that heats and vaporizes the liquefied gas introduced thereinto is provided; a guide-out path, through which the liquefied gas is guided out from the liquefied gas storage section to the inner heat-blocking chamber, is formed between the liquefied gas storage section and the inner heat-blocking chamber; the supply path is connected to the liquefied gas storage section, characterized in that an end of the reflux path is connected to a gas phase space in the liquefied gas storage section that is above the liquefied gas, whereby the supply path and the reflux path are independent from each other; an outlet through which the vaporized gas flows out to the reflux path is formed in a top part of the inner heat-blocking chamber; and used as a heating medium for the heat exchange section is the gas that circulates in a heating medium circulation path that extends from the inside to the outside of the tank to circulate gas, a part thereof that is located inside the tank being the heat exchange section.