Disclosed is a method of producing an expanded tobacco material. According to the method, a tobacco material (TM) is fed into a pressure vessel (11), followed by pressurizing the interior of the pressure vessel (11) with a carbon dioxide gas to a predetermined impregnation pressure. Then, a liquid carbon dioxide (21) is supplied from above the tobacco material (TM) into the pressure vessel through a sintered metal plate (13), etc., while maintaining the impregnation pressure, thereby saturating the interior of the pressure vessel (11) with a carbon dioxide gas generated by vaporization of the supplied liquid carbon dioxide, and cooling the tobacco material by the latent heat of vaporization of the liquid carbon dioxide, so as to impregnate the tobacco material with carbon dioxide. The tobacco material impregnated with carbon dioxide is brought into contact with a hot gaseous stream within a gaseous stream dryer so as to expand the tobacco material.