Abstract: A telescopic shaft including a male shaft including a plurality of first splines formed on an outer circumferential surface in an axial direction and a fixing groove and a derail prevention protrusion which are formed on outer circumferential surfaces at one end and a middle portion of the male shaft in a radius direction, a female shaft including a hollow and a plurality of second splines formed on an inner circumferential surface of the hollow corresponding to the plurality of first splines, a plurality of balls disposed between grooves of the plurality of first splines and grooves of the plurality of second splines, a leaf spring having a plate shape and inserted into the plurality of first spline grooves, and a fixing ring connected to the fixing groove and surrounding one end of the leaf spring to prevent the leaf spring from derailing.