The present invention relates to a automatic cup cleaning apparatus, which is capable of preventing various foreign substances from entering into the cup after washing in the process of automatically cleaning and sterilizing the cup, while simplifying the driving sequence to facilitate continuous operation without failure Developed； A cup washing section for spraying water to the inner and outer surfaces of the cup introduced by the washing nozzle to wash the cup； and a hot air blower for blowing hot air into the cup cleaned by the hot air spray nozzle, A cup sterilizing unit for sterilizing the cup by a UV sterilizing lamp； and a cup discharging unit for discharging the cup, the apparatus comprising: The cup washing unit, the cup drying unit, and the cup sterilizing unit are sequentially arranged from the upper part to the lower part, and the driving shaft rotated by the driving motor vertically passes through the center. An inner ring having a shape of a ring and seated on an upper surface of the seating bar, and a plurality of bearing bars extending from the outer ring in a radial direction at regular intervals, And an outer ring having an interval smaller than an upper diameter of the cup and being seated on the upper surface of the seating bar. The outer ring is mounted on the inner lower portion of the cup washing portion, the cup drying portion and the cup sterilizing portion, And a rotary disk for moving the cup placed on the ring； The cup insertion portion includes a pair of sliding wires extending parallel to each other at an interval smaller than the diameter of the cup and a flat plate placed in a state where the cup is turned upside down and extending in an inclined downward direction and extending tangentially to the inner ring and the outer ring, And a cup passing hole passing between the flat plate and the sliding wire in a trapezoid having a width wider than that of the upper portion so that the cup can pass through only the inverted state； The cup
