PURPOSE: To provide a support forming method in an optical shaping method capable of selectively supporting the overhung part of a shaped article and easin in support removing work after shaping.

CONSTITUTION: Since a predetermined gap 2a is provided between a shaped article 1 and a support 3 when unit photoset layers 3a, 1a are formed on an XY plane, a gap 17 is opened between the perpendicular surface 11 or inclined surface (non-overhung inclined surface) of the shaped article 1 and the support 3 and the support 3 is not connected to the shaped article 1. When an overhang angle becomes a certain degree or more, the end part of the unit photo-set layer 1f of the shaped article rides on the upper part of the unit photo-set layer 3e of the support just thereunder. Therefore, the overhung part 15 of the shaped article 1 is selectively supported and, in a region other than the part 15, the shaped article 1 and the support 3 are not connected. As a result, since the connection part of the shaped article and the support is minimized, support removing work after shaping becomes easy.