PURPOSE: To enhance the holding force of a catalyst compsn. and to also enhance the peel strength of a metal lath base material even to which no flame spraying is applied by forming notch like unevenness specified in depth and size to the surface of the metal lath base material of a catalyst.

CONSTITUTION: Notch like recessed and protruding parts 2 having depth which is larger than the diamdter of a catalyst compsn. and a reinforcing fiber to be mixed and desirably 10μm or more and equal to or less than 1/2 or less the thickness of a thin metal plate and a pitch smaller than the dimension of lath meshes 3 are mechanically formed on the thin metal plate to roughen the surface thereof. Thereafter, metal lath processing is applied to this metal plate to obtain a base material. The catalyst compsn. enters the notch like recessed and protruding parts 2 and, even when the number of the recessed and protruding parts 2 is less, the drying shrinkage of a catalyst paste is suppressed in the same way as flame spraying. Since the crossing part of each of the notch like recessed and protruding parts 2 and a lath notch cross section is sharpened in its end part, the crossing part functions as the mechanical resistance part to the detachment of the catalyst compsn. to impart holding force to the catalyst compsn.