Abstract: This support member for additive manufacturing is a support to be disposed below a manufactured portion of a particular overhanging portion of the three-dimensional object which needs the support in the process of additively manufacturing the three-dimensional object. The support member is provided with: the support main body; and a polishing channel which is formed in the support main body so as not to be exposed to an interface with the three-dimensional object, and through which a polisher for polishing and removing the support main body is allowed to pass.