Disclosed is an automatic detachable door of a detachable type for a showcase. The automatic detachable door includes a plurality of foldable screens (30), of which a cover cap (40) is respectively fitted into upper and lower portions of the respective foldable screens (30), a first fitting protrusion (41) is mounted to one side of the upper cover cap (40), and a second fitting protrusion (47) is mounted to one side of the lower cover cap (40); and upper and lower frames (20 and 22) which are provided with a plurality of fitting holes (23) at a certain interval. Power transmission members (70) are fitted into the fitting holes (23) of the upper frame (20). A center of the power transmission member (70) is provided with a protrusion receiving hole (71) for receiving the first fitting protrusion (41). Two rod receiving holes (73) are formed at symmetric positions at an equal distance from a center the protrusion receiving hole (71). A coil spring (81) and a powered rod (80) are sequentially inserted into the respective rod receiving holes (73). An upper portion of the protrusion receiving hole (71) is provided with a locking shoulder (72) on which a holding bolt (46) for holding the first fitting protrusion (41) is seated. An upper portion of the first fitting protrusion (41) is provided at a center thereof with a fastening hole (45) to which the holding bolt (46) is fastened. A lower portion of the first fitting protrusion (41) is provided with a protrusion body (42) having an outer diameter larger than an outer diameter of the first fitting protrusion (41). A top surface of the protrusion body (42) is provided with two seating holes (43) at two symmetric positions at an equal distance from the center of the first fitting protrusion (41), in which the seating holes (43) are formed to receive front ends of the rods (80). The protrusion body (42) is engaged to a protrusion body seating member (44) formed on a top surface of the cover cap (40). The plurality of foldable screens (30) are simultaneously opened or closed by a rotating member mounted to the upper frame (20).