To provide a joint member which can easily join long building materials and which can ensure a sufficient joint strength.

A joint member 50 for joining long building materials 21, 41 formed therein longitudinally extending hollow parts 29, together, is composed of a body part 51 laid along end parts of the long building materials 21, 41, and joint protrusions 52, 53 which are projected from the body part 51 and which can be fitted in the hollow parts 29 of the long building materials 21, 41. With this arrangement, the long building material can be rapidly coupled together end-to-end only through the joint protrusions 52, 53 and the body part 51 by press-fitting the joint protrusions 52, 53 into the hollow parts 29 of the long building materials 21, 41 with a sufficient joint strength.