A three-dimensional shaping method in which after formation of a powder layer with a predetermined thickness, a step for sintering the powder layer by an optical beam is performed at a predetermined number of times and, thereafter, a periphery thereof is cut, comprising that a control system stores in advance a region at coordinate positions in a horizontal direction and a height direction in which an undercut angle formed between an upper face and a lower inclined face at the edge of an expected sintered part is equal to or less than a predetermined extent corresponding to a cause for forming a raised sintered portion on each layer, and when the region at the coordinate positions is present on an individual layer to be sintered, the control system temporarily stocks the region at the coordinate positions, and also after sintering of the layer concerned is completed, at an intermediate height position between the position of the surface on which the sintering concerned has been completed and the lowest position of a powder supplying blade moving in the horizontal direction for forming a powder layer on a next layer on the upper side of the layer concerned, a rotating cutting tool travels around the region at the coordinate position in the horizontal direction and an outer peripheral vicinity thereof according to instructions of the control system, thereby, in the case that a raised sintered portion is formed which is positioned on the upper side of the region at the coordinate position, the rotating cutting tool cuts the raised sintered portion entirely or partially with detecting in advance the cause for forming a raised sintered portion on each layer in a stage before the formation of a next layer positioned on the upper side of the layer concerned, or that on an individual layer to be sintered, a scanning position at the end of a scanning site of an optical beam is increased horizontally in region and in a state of projecting to a greater extent than a scanning position at the edge of the optical beam on an immediately preceding sintered layer positioned so as to be adjacent to a lower side of the layer concerned at a position lower than the scanning position concerned, and also a height width between both ends thereof is divided by a horizontal width to calculate a ratio, and when the ratio is determined to be equal to or less than a predetermined number corresponding to a cause for forming a raised sintered portion on each layer, a control system temporarily stocks coordinate positions in a horizontal direction and a height direction at the projection end in which the ratio is determined to be equal to or less than the predetermined extent and in a vicinity region thereof, and also after sintering of the layer concerned is completed, at an intermediate height position between the position of the surface on which the sintering concerned has been completed and the lowest position of a powder supplying blade moving in the horizontal direction for forming a powder layer on a next layer on the upper side of the layer concerned, a rotating cutting tool travels around the region at the coordinate position in the horizontal direction and an outer peripheral vicinity thereof according to instructions of the control system, thereby, in the case of a raised sintered portion forming on the upper side of the region at the coordinate position, the rotating cutting tool cuts the raised sintered portion entirely or partially with detecting in advance the cause for forming a raised sintered portion on each layer in a stage before the formation of a next layer positioned on the upper side of the layer concerned.