PURPOSE: To simplify a work to mounting a plate, such as partition walls, to execute a work at a low cost, and to firmly support various plates.

CONSTITUTION: By bending a metallic sheet, for example, galvanized sheet, a vertical long columnar stay material 12 and a T-shaped plate mounting member 15 consisting of a vertical piece 15A and a horizontal piece 15B are integrally formed. Two side edges 15Bb of the horizontal piece 15B of the plate mounting member 15 is positioned inside two flanks 12a of the stay material 12. The two side edges 15Bb of the horizontal piece 15B of the plate mounting member 15 are prevented from being an obstacle and easily fitted in respective recessed grooves 17 of a wall plate material 30 and the manufacturing cost of the stay 10 can be reduced.