A separator plate useful in a wet-type multiplate clutch is provided on a friction surface thereof with elongated asperities extending with regularity in a predetermined direction. Peak portions of the elongated asperities, said peak portions being to project toward a counterpart member when the separator plate is assembled in the wet-type multiplate clutch, have been removed to form elongated plateaus. The separator plate can be manufactured by fixedly mounting a blank for the separator plate on a work support, forming elongated asperities with regularity in a predetermined direction on one of opposite surfaces of the blank by a grinding wheel, and then removing peak portions of the elongated asperities, said peak portions being to project toward a counterpart member when the separator plate is assembled in the wet-type multiplate clutch, to form elongated plateaus.