Abstract: A build system includes: a build apparatus including an energy beam irradiation unit, a material supply unit, and a control apparatus. The build system builds a second object above a first object including a first space. The second object includes: a first inclination part connected to the first object; a second inclination part connected to the first object; and a connection part that connects a tip of the first inclination part and a tip of the second inclination part. The build system builds the first inclination part and the second inclination part by alternately performing a building of a part of the first inclination part and a building of a part of the second inclination part. A second space below the first inclination part and the second inclination part is connected to the first space, and an upper part of the second space is closed by the connection part.