Abstract: Apparatus for manufacturing a three-dimensional shaped object comprises a chamber, a transmission window, a blow-out port and a cover member, wherein a solidified layer is formed by irradiation of a predetermined portion of a material layer with a light beam, thereby allowing a sintering of the material in the predetermined portion or a melting and subsequent solidification of the material, the material layer being provided within the chamber. The transmission window is provided in the chamber, allowing the light beam to be transmitted there through. The blow-out port is located around the transmission window, and serves for blowing out an inert gas toward an interior of the chamber. The cover member, which is positioned below the blow-out port and also serves for surrounding the blow-out port, has an annular form. A gap through which the inert gas-passes is provided between the cover member and the transmission window.