PURPOSE: To improve work efficiency and to promote man-power saving by dropping a girder having the front end inclined to the side of a joint bracket into a girder bearing plate projected to the side of the girder from the lower part of the joint bracket, and inserting a guide pin into a guide-hole.

CONSTITUTION: The joining ends S1 and S2 of a column - girder joint bracket 1 with a girder 2 have such joint constructions that the upper parts of them are inclined to the side of the joint bracket 1 and that the lower parts are inclined to the side of the girder 2. The girder 2 equipped with a guide pin 21 having the front end inclined to the side of the joint bracket 1 to the bottom is dropped into a girder bearing plate 12 projected to the side of the girder 2 provided with a guide hole 113 from the lower part of the joint bracket 1. After that, the guide pin 21 is inserted into the guide hole 113 to position.