A keyboard attached to a personal digital assistant (PDA) set having: a hinge unit including a connector to transfer a keyboard input signal to the PDA, and upper and lower hinge covers; a connection unit placed inside of the hinge unit, and can be attached in the front direction or the back direction to the PDA; and a keyboard body connected with the hinge unit, folded and unfolded about the hinge unit, having a typing board on an upper side and a front panel controller (FPC) keypad to input a key pressed on the typing board. Therefore, the keyboard of the PDA can not only be attached in the front direction or the back direction to the PDA, but also separated from the PDA, thus making the usage and maintenance of the keyboard convenient.