A high-pressure tank producing apparatus capable of reducing time for increasing temperature of a tank body. The apparatus that heats the tank body with fibers impregnated with a thermosetting resin wound around its surface includes a heating chamber for housing the tank body and a retaining mechanism for retaining the tank body within the heating chamber, in which the heating chamber has an injection port for injecting heated gas onto the surface of the tank body and an exhaust port for discharging the gas to the outside of the heating chamber, the exhaust port being disposed in a position where the injection port is projected in a gas injecting direction, and the retaining mechanism retains the tank body in a region where the injection and exhaust ports overlap with each other as viewed from the gas injecting direction and in a position between the injection and exhaust ports.