To provide a hot brush heated for hairdressing, requiring no power supply, and convenient to carry.

A cover 4 is openably provided at the cylindrical tip of a brush main body 1, and an expendable cartridge 2 can be fitted into it or removed from there. Water and quick lime are separated by an aluminum seal and stored in the cartridge 2. When the switch knob 3 of the brush main body 1 is operated, a shaft slid in the cartridge 2 is pressed by the extension section of the switch knob 3, an actuator at the tip of the shaft pierces the aluminum seal, water and quick lime are mixed and reacted to generate heat, and heat is transferred to the brush hair face 11 of the brush main body 1 where brush hairs 10 are planted to allow hairdressing. The cartridge 2 is small-sized, and a spare one can be easily carried.