To provide a hair material for a brush, which does not form a dent and a fine flaw on a surface to be washed, and is used for various washing brushes and various cleaning brushes which show high washability.

A hair material 1 for a brush has the form of multifilament which is formed by preparing a plurality of monofilament yarns 2 and 3 that are made of a thermoplastic resin and have a basically columnar shape, melting and bonding the yarns 2 and 3, and bundling the yarns 2 and 3 at a joining part 5 formed by using an extended part 4 having an approximately projected shape. In addition, the bonded monofilament yarns 2 and 3 are formed so as to be capable of being separated from the joining part 5 or a vicinity of the joining part 5 by the application of external force.