A position pin (20) is pushed down by an effort applied on a control button (27) to disengage the position pin (20) from a position plate (18) when a selector lever is to be moved from a parking position to other gear positions. A bushing (28) is mounted on a post (14) of the selector lever for rotation but against axial movement. The bushing has at the upper end a pair of diameterically opposed notches (29) with which the position pin is engaged when pushed down to effect the above disengagement. When an ignition key is at the "ON" position and the selector lever is at the parking position, the bushing is rotated into a position where the notches are misaligned with the position pin unless a brake pedal is fully depressed, i.e., an effor applied on the control button for pushing the position pin downward is received by the upper end of the bushing whereby downward movement of the position pin for disengagement thereof from the position plate is prevented by the bushing and therefore it is impossible to move the selector lever from the parking position to other gear positions. In accordance with the present invention, there are further provided various safety means for preventing the positon pin from being errorneously aligned with the notches.