PURPOSE: To provide a masking method capable of improving coating efficiency wherein a masking material composed of a permanent magnet and having a positioning means is held by attraction on the part desired to be left uncoated of the object formed of magnetic material.

CONSTITUTION: A masking material 10 is composed of a permanent magnet and the bottom 22 of a body part 12 is given such a shape as to conform to the part desired to be left uncoated of an object to be coated. A projecting part 14 is provided for positioning the masking material 10 by being inserted into the hole preformed in the uncoated part of the object. To provide an uncoated part 28 around a threaded hole 26 in a chassis 24, the projecting part 14 of the masking material 10 is inserted into the threaded hole 26 in order for the masking material 10 to be positioned and also held closely on the chassis 24 by its own magnetic force. The part 28 is free from contamination with coating material 30, since it is masked closely by the bottom surface of the body part 12 of the masking material 10 when the object is coated.