PURPOSE: To apply the desired amount of thermoplastic resin on a reticulate structure consisting of heat-resistant fibers without generating clogging of meshes due to applied resin.

CONSTITUTION: Thermoplastic resin films 2 are laminated on the upper and lower surfaces of a reticulate structure 1. Soft sheet type materials 3a are laminated on the upper and lower surfaces thereof and mold parting sheets 5 are superposed on the outside thereof if necessary, then, the laminate is pressed under heating by hot press boards 4. The thermoplastic resin films are welded by fusion to each other through the meshes thereof. The laminate is heated at a temperature higher than the melting point of the thermoplastic resin films to aggromerate the thermoplastic resin films. Spaces are formed in the meshes while the surfaces of the fibers of reticulate structure are coated by the thermoplsatic resin.