To firmly couple together a column and a sill by a method wherein the horizontal part piece of a coupling frame made of a steel plate in a U-shape is located between the end face of the column and the sill, and the tenon of the column is engaged with the tenon hole of the sill through a window hole, and a lock lever is driven in a through-hole.

A steel plate is press-molded, and a coupling frame A1 is formed such that a horizontal piece 3 and vertical part pieces 4 and 4 positioned facing each other at the to ends of the horizontal part piece 3 are coupled together. A plurality of through-holes 6 are arranged in each of part pieces 3 and 4 and a window hole 8 is formed in the horizontal part piece 3. the horizontal part piece 3 of the coupling frame A1 is located between the end face of a column and the peripheral side of a sill. The tenon of a column is engaged with the tenon hole of the sill through the window hole 8, and a lock lever is driven in the through-hole of the horizontal part piece 3 to fix the sill. Further, the lock lever is driven in the through-hole 6 of the vertical part piece 4 and fixed at the column. By using the coupling frame A1, coping with a change with the lapse of a time of a longitudinal material or a lateral material is practicable. Further, the weight of the longitudinal material or the lateral material is uniformly distributed by a horizontal part piece 3.