PURPOSE: To prevent a friction material from protruding from the fixed position thereof when it is bonded, by providing a concave or convex part just inside or outside of a position on a metal plate whereat the friction material is fixed, while providing a convex or concave part on a press die which conforms with the one on the metal plate.

CONSTITUTION: On the occasion when a friction material 1 is bonded to the inner or outer circumferential part of an metal plate (ex. iron plate) 2, a small concave 4 (a circumferential groove formed along the imediate inside of the inner circumference of the friction material 1 in an example shown in the figure) is fomed just inside or outside of a position on the metal plate 2 whereat the friction material 1 is fixed, while a convex part (not shown in the figure) is formed on a bonding die or a press die for primary vulcanization so that it fits in the above concave 4. When a bonding operation or an operation for pressurization and heating together with primary vulcanization is performed, the concave 4 and the convex part on the die are made to fit to each other, and thereby the rubber of the friction material 1 is prevented from protruding from the fixed position thereof.