A shift/tilt locking apparatus for shift lever of automatic transmission may include a shift knob, a main shaft slidably and rotatably disposed in a housing such that shift knob is slidable; a crossbar having shift knob at the upper end to tilt; a shift restriction device that allows shift knob to slide by selectively restricting sliding of main shaft; and a tilting restriction device controlling shift knob to tilt by selectively restricting the tilting of shift knob by using a third solenoid, which is controlled by a shift mode determining step that determines a shift mode by checking the position of shift knob and a lever locking step that restricts/releases shift knob by selectively operating first solenoid to third solenoid.