A method for preventing irregular packaging for automatic medicine packing machine having a last hopper that contains the tablet just before the tablet is packed, includes steps of sensing whether a tablet is received in the last hopper, sensing and deciding whether the tablet stands vertical inside the last hopper, vibrating a shutter if it is decided that the tablet stands vertical whereby the vertical standing tablet falls down, and checking non-standing of the tablet after completion of shutter vibration. The apparatus performing the method includes a shutter vibrating unit and a standing sensor that is installed on the last hopper and senses whether the tablet received in the last hopper stands vertical. The standing sensor includes a horizontal slot that is formed horizontally at a side of the last hopper at a position corresponding to a vertical height of a tablet and a photo sensor.