A roller skate includes a shoe body and a wheel portion comprising a front wheel assembly and a rear wheel assembly. The front wheel assembly and the rear wheel assembly can be easily attached to or detached from an underside of the shoe body without tools. The present invention provides a shoe that can be easily converted from a walking or running shoe to a roller skate and vice versa. It is comfortable for the wearer to skate with such roller skate. Moreover, there is no limitation to the size of the roller.