PURPOSE: To carry out efficient junction by extruding engagement holes opened to end faces in the extruding direction to extrusion materials at the same time.

CONSTITUTION: Aluminum extrusion materials 1 are provided with plural inverse L-shaped ribs 3 joined vertically, at an interval, in parallel and integrally on thin flat plate parts 2. The rib 2 consists of a thin part 3a and a thick part 3b. An engagement hole 5 is formed on the extrusion material (π section material) 1 to engage a pin 4 for controlling the irregularity between engagement holes to an end face in the extruding direction. These engagement holes 5 are extruded simultaneously when they are extruded. The extrusion materials 1, 1 are engaged as the control pin is passed through the engagement holes 5, 5 and both materials 1, 1 are thrusted each other. In this way, the extrusion materials can be held in an adjustable connective state to other members.