A castor includes a main body, two rollers, a plurality of rolls, two retaining members, and two covers. Thus, the rolls are rotatably mounted between the main body and the respective roller, so that each of the rollers is rotatable on the main body smoothly. In addition, the rolls and the rollers are made of the same material to reduce the friction between the rolls and the rollers during rotation of the castor, so that the rolls and the rollers are not easily worn out during a long-term utilization. Further, the rollers are covered by the covers so that only the through hole of the main body is exposed outwardly from the covers and the rollers, thereby enhancing the aesthetic quality of the castor.