The present invention is to offer a gas mist pressure bath device which is possible to cause a skin or mucous membrane of a living body to efficiently absorb gas of an even small amount, and can attain to make the device compact and reduce cost. This is the device 10 for causing oxygen, carbon dioxide, or a mixed gas (called as “gas” hereafter) of oxygen and carbon dioxide at a density of not less than a predetermined value to contact the skin or mucous membrane of the living-body, this device comprises a gas mist generating means 11 for generating and supplying a mist (called as “gas mist” hereafter) prepared by pulverizing and dissolving the gas and liquid, and a bag shaped living-body cover member 12 for covering the living-body's skin or mucous membrane and sealing inside thereof the gas mist from the gas mist generating means 11, and a pressurizing means of the living-body cover member 13, and the gas mist sealed within the living-body cover member 12 is caused to contact the skin or mucous membrane of the living-body at pressure higher than the predetermined value by means of the pressurizing means of the living-body cover member 13.