An evaporative gas generating device comprising: a container provided with a liquid accommodating part that accommodates a liquid, and an evaporative gas accommodating part that is continuously provided above the liquid accommodating part and introduces evaporative gas formed by the liquid within the liquid accommodating part being evaporated; and a heating unit (35, 36) that heats both the liquid accommodating part and the evaporative gas accommodating part to evaporate the liquid within the liquid accommodating part and raises the temperature of the evaporative gas within the evaporative gas accommodating part, wherein the heating unit is disposed on at least one of the inside of the inside bottomed tubular member or the outside of the outside bottomed tubular member, a liquid introduction part that introduces the liquid into the liquid accommodating part; a discharge part that discharges the evaporative gas formed by the liquid being evaporated from the evaporative gas accommodating part; a liquid level detecting unit that detects the height of a liquid level of the liquid within the container; and a liquid level control unit (42, 43) that controls the liquid introduction part on the basis of a detection result of the liquid level detecting unit to adjust the amount of introduction of the liquid into the liquid accommodating part so that the height of the liquid level falls within a certain range, wherein the container has a double structure including two bottomed tubular members (11, 12), a lower part of a space formed between the inside bottomed tubular member and the outside bottomed tubular member forms the liquid accommodating part, and the upper part of the space forms the evaporative gas accommodating part, wherein the bottom surfaces of the inside bottomed tubular member and the outside bottomed tubular member form a convex surface that protrudes downward, and the inside bottomed tubular member is housed inside the outside bottomed tubular member. a container provided with a liquid accommodating part that accommodates a liquid, and an evaporative gas accommodating part that is continuously provided above the liquid accommodating part and introduces evaporative gas formed by the liquid within the liquid accommodating part being evaporated; and a heating unit (35, 36) that heats both the liquid accommodating part and the evaporative gas accommodating part to evaporate the liquid within the liquid accommodating part and raises the temperature of the evaporative gas within the evaporative gas accommodating part, wherein the heating unit is disposed on at least one of the inside of the inside bottomed tubular member or the outside of the outside bottomed tubular member, a liquid introduction part that introduces the liquid into the liquid accommodating part; a discharge part that discharges the evaporative gas formed by the liquid being evaporated from the evaporative gas accommodating part; a liquid level detecting unit that detects the height of a liquid level of the liquid within the container; and a liquid level control unit (42, 43) that controls the liquid introduction part on the basis of a detection result of the liquid level detecting unit to adjust the amount of introduction of the liquid into the liquid accommodating part so that the height of the liquid level falls within a certain range, wherein the container has a double structure including two bottomed tubular members (11, 12), a lower part of a space formed between the inside bottomed tubular member and the outside bottomed tubular member forms the liquid accommodating part, and the upper part of the space forms the evaporative gas accommodating part, wherein the bottom surfaces of the inside bottomed tubular member and the outside bottomed tubular member form a convex surface that protrudes downward, and the inside bottomed tubular member is housed inside the outside bottomed tubular member.