To change the height of a beam material in response to application, and to obtain specified strength.

In the assembly type beam material 1, a beam material 100 is separated into an upper chord material 2, a lower chord material 3 and adjusting materials 4, and the upper chord material 2 and the lower chord material 3 are formed of an extruded material. Engaging groove sections engaged with the end sections of the adjusting materials 4 are formed to the connecting sections 2a, 3a of the upper chord material 2 and the lower chord material 3, and the adjusting materials 4 are interposed between the connecting sections 2a, 3a of the upper chord material 2 and the lower chord material 3. One end sections of the adjusting materials 4 are engaged with the engaging groove sections of the upper chord materials 2 and the other end sections with the engaging groove sections of the lower chord material 3, and the adjusting materials 4 and the upper chord material 2 and the lower chord material 3 are joined by connecting materials.