To provide a setting-up method of a girder material and a column material, in which the periphery of a mortice is worked to an off-spec girder material having long size or short size between a top face and an underside or a girder material conformed to standard size.

A mortice 4a is worked to the girder material 4, surface-sinking working is executed to a section 4b in the periphery of the mortice 4a by width A, and the working is conducted so that width B between the top face and underside of the girder material 4 reaches predetermined width. Since width B between the top face and underside of the section of the mortice 4a of the girder material 4 can be set at a predetermined value by executing surface-sinking working to the section 4b of the mortice 4a of the girder material 4 by width A at that time even when width (A+B) between the top face and underside of the girder material 4 variously differs, the whole top face and underside of the girder material 4 need not be worked even when width between the top face and underside of the girder material 4 is longer or shorter than standardized size, and surface-cleaning working is executed only to the section 4b in the periphery of the mortice 4a, thus extremely improving operating efficiency.