A conventional undercoating method in repair painting on a damaged vehicle, which includes many working processes, possesses drawbacks of being low in working efficiency and making a finally repaired area exceedingly larger than an initial damaged area. A network of words and syllables is generated, and the network has two kinds of paths: paths that do not contain a particular syllable and paths that contain the syllable at a position corresponding to a boundary between words. The body is replaceably mounted either on the top or on the bottom of the shelf.