To provide a structure for securely and stably attaching a pedestal for components to be attached thereon on a gatepost even though the gatepost is columnar.

A columnar gatepost 1 is provided with an attachment slot 2 cut in the vertical direction on its outer surface with projecting pieces 3 placed opposing to each other on both outer sides of the openings of the attachment slot 2. The gatepost 1 is also provided with latching slots 10 cut in the vertical direction on both sides of the attachment slot 2. A backboard 4 for fixing a pedestal is inserted in the attachment slot 2 so that the backboard 4 can slide up and down freely. A back surface 12 of the curved surface of a pedestal 11 for components to be attached is placed to follow the shape of the outer surface of the gatepost 1. At this time, latching projections 13 on both sides of the back surface 12 are caught by the latching slots 10. Then, fixing bolts 14 are inserted though the pedestal 11 and the back board 4 via the openings of the attachment slot 2 and then tightened in order to tightly fasten the projecting pieces 3 between the pedestal 11 and the back board 4.