A mechanism is provided for controlling vehicle ignition lock (4) and transmission shift lock (1) in an interlocked relation to each other. The mechanism comprises a lock member (5) movable into a lock position for blocking up a passage (37) to a Park position of a position plate (3). An operating member (6) drives the lock member (5) into the lock position in response to upward movement of a position pin (21) in the Park position. A stopper (41) of an ignition lock is movable between a lock position for preventing rotation of a key rotor into a lock position and an unlock position for allowing the same. A cable (7) interconnects the lock member and the stopper to allow them to move in unison such that movement of the lock member into the lock position causes the stopper to move into the unlock position and movement of the stopper into the lock position causes the lock member to move into the unlock position. A spring (44) is installed in the ignition lock for urging the stopper toward the lock position.