To provide a bearing of a seal structure excellent in dust proof effect and easy to assemble, and provide a motor assembly in which the bearing is assembled.

A bearing metal 8a is fit to a supporting frame 7a, a seal housing recessed part 13 is arranged thereon, a shaft 6 is arranged penetrating the bearing metal 8a and the seal housing recessed part 13, and a ring shaped seal 10a is press-in-fit to the outside of the shaft 6 so as to form it in the same surface as the inner surface of a supporting frame. A labyrinth structure is formed between a seal and a seal housing recessed part 13, and sealing effect is improved. The surface of the seal is fit to the upper surface of the supporting frame, and thereby, assembly is carried out easily.