An automatic lathe is provided which is capable of rapidly and easily switching between machining of a material with a guide bush and machining of the material without the guide bush. The automatic lathe has a guide bush support table (1) disposed closer to a tip side of a spindle (3) than a head stock (6); support table fixing means (15) for fixing the guide bush support table (1); a guide member (12) rotatably installed on the guide bush support table (1) so as not to move forward and backward; a guide bush (4) detachably fitted to the tip of the guide member (12); driving means (11) for rotating the guide bush (4); rotation transmission means (14a) and (31) for transmitting the rotation of the guide member (12) to the spindle (3); spindle moving means (7) for moving the spindle (3) forward and backward within the guide member (12); and spindle fixing means (17), (36) and (38) for positioning and fixing the spindle (3) at a specified position on the guide bush support table (1) when the guide bush (4) is removed from the guide member (12).