A brake device for a motor vehicle seat is composed of a brake assembly, a tooth assembly, and a lever assembly. The brake assembly includes a housing, a pinion shaft, a braking component, and a drive wheel that are structured to be self-held in an assembled state by mechanical interaction thereamong. The tooth assembly includes a holder plate and a tooth plate that are structured to be self-held in an assembled state by mechanical interaction therebetween. The lever assembly includes an input lever, a cover, a coil spring, and a lever bracket that are structured to be self-held in an assembled state by mechanical interaction thereamong. The brake assembly, the tooth assembly, and the lever assembly are arranged and assembled together in an axial direction.