PURPOSE: To safely and easily carry out the fitting work and reduce the construction time, by inserting the pin of a metal fixture into a fitting hole and holding tone connection side of a frame and the supporting side of a girder.

CONSTITUTION: A jointing structure of a frame is provided with a metal fixture 11 of which one end of an elastic bar is vertically bent downward to make a pin 14 and the other end thereof is bent to show a nearly U-shaped in the side view to make a fitting part 15. Next, a nearly U-shaped installation base 6 is welded at the under face of the front of the frame 2 and a vertical bolt, hole 8 is formed on the horizontal connection plate 7 at the lower end thereof. And a bolt hole 10 corresponding to the bolt hole 8 of the connection plate 7 is formed on the flange 9 at the upper side of of the girder 12. Then both bolt holes are superimposed and also the connection plate 7 of the installation base 6 is stacked on the flange 9 of the girder 12. And a pin 14 of the metal fixture 11 is inserted into both bolt holes 8, 10 and further, the fitting part 15 is hammered from the outside to fix time connection plate 7 and the flange 9 together.