A method for producing a three-dimensionally shaped object, includes the steps of: (i) forming a solidified layer by irradiating a light beam on a specified portion of a powder layer placed on a shaping table to sinter or melt the specified portion; (ii) forming another solidified layer by placing a new powder layer on the solidified layer thus obtained, and irradiating the light beam on a specified portion of the new powder layer to sinter or melt the specified portion of the new powder layer; and (iii) repeating the step (ii) to produce a three-dimensionally shaped object. When performing the steps (i) to (iii) within a chamber, at least a part of an ambient gas in the chamber is exhausted from the chamber through a gas passage of a shaping tank.