To provide a junction member facilitating junction and detachment of two plate materials while improving junction force and adaptable even when a through hole cannot be formed on one of the two plate materials.

This junction member is composed of a key member 1 and a key receiving member 2. The key member is composed of a head 3, a shaft part 4 extended substantially perpendicular to a surface of the head 3, and a key part 5 formed on a tip of the shaft part 4 protrusively in the direction substantially perpendicular to the axial direction of the shaft part 4. The key receiving member 2 has a hole part 6 of a shape corresponding to the key part 5. The two plate materials are joined by inserting the shaft part 4 through a through hole H1 of one plate material W1, rotating the key part 5 a predetermined angle in a state inserted through the hole part 6, and locking the key part 5 to an opening rim part of the hole part 6.