To provide a connection structure between a column and a beam, in which an end of the beam can be mounted on a lower outer diaphragm of the column by allowing an end of the beam to pass through a notch so as to be dropped onto the same, and to provide a method of connecting between the column and the beam, which is so excellent in workability as to horizontally erect the beam between the columns only by allowing the beam to pass through the notch so as to be dropped onto the lower outer diaphragm, and by temporarily securing the beam to the columns by means of bolts.

The connection structure 1 between the column and the beam is comprised of an upper outer diaphragm 7 and the lower outer diaphragm 8 which are annularly fitted on the column 2, gusset plates 10 to which webs 6 are connected, the notches 9 formed in the upper outer diaphragm 7, and splice plates 11 for an upper flange. The method of connecting between the column and the beam is comprised of the following steps. In the dropping step, the beam 3 is vertically lowered from above the notch 9 and allow the beam to pass through the notch 9 so as to be dropped. In the temporary securing step, the lower outer diaphragm 8 and a lower flange 5 of the beam 3 are temporarily secured to each other by the bolts.