When a molded fabric body (X) is impregnated with a powder (K) of a predetermined material, there are performed a first step of dispersing the powder (K) in a liquid to prepare a slurry, and a second step of burying the molded fabric body (X) made of fiber bundles in the slurry and vibrating the slurry by use of a predetermined vibrator (M). Furthermore, in the second step, the vibrator (M) is moved along a surface of the molded fabric body (X). As a result, it is possible to improve the rate of impregnation of the powder (K) more than that in the conventional cases, irrespective of the shape of the molded fabric body (X).