A key interlock mechanism for a column automatic-transmission operating device includes a key lock lever having one end with a slot and swingably supporting the lock pin through the slot, a shank formed with the key lock lever, a guide groove formed with a unit base and cooperating with the shank to rotatably support the key lock lever so as to bias a lock pin in the direction of protruding into a key cylinder, and a key lock lever spring wound around the shank for biasing the key lock lever so that the lock pin protrudes into the key cylinder and for returning to a given position another end of the key lock lever which has moved along the guide groove.