To provide a bristle material for a brush, having excellent properties wherein excellent cleanability and touch properties continue for a long period because peeling durability between a core part and a sheath part, or between an island part and a sea part is extremely high as compared to a conventional bristle material for the brush wherein the core part or the island part is exposed in the bristle tip, and allowing easy processing by use of a conventional chemical amount reduction method.

The bristle material 1 for the brush consists of a synthetic resin monofilament having a core-sheath composite structure. The core part 4 consists of polybutylene naphthalate, and the sheath part 5 consists of a polyester-based resin other than polybutylene naphthalate. At least one end of the synthetic resin monofilament has a tip bristle wherein the core part 4 is exposed from the sheath part 5.