To provide a method for manufacturing a three-dimensional shaped object in which a three-dimensional shaped object is manufactured by discharging a shaping material from a discharge unit toward a stage to stack a layer, the method for manufacturing a three-dimensional shaped object includes: a first step of generating path data having a plurality of partial paths through which the discharge unit moves while discharging the shaping material; a second step of determining a line width of the shaping material in each of the partial paths and generating line width information for implementing the line width; a third step of generating shaping data including the path data and the line width information; and a fourth step of shaping the three-dimensional shaped object according to the shaping data. In the second step, the line width in a target path that is one of the partial paths is determined in accordance with a distance between a first wall and a second wall separated by the target path. The first wall and the second wall are side edges of the shaping material discharged in the partial path generated before the target path or a contour line of the three-dimensional shaped object.