The invention relates to a container separator apparatus for automatically separating stacked rimmed containers. The container separator apparatus utilizes at least one spindle comprising a rotation cylinder, a screw-toothed cylinder, and a semi-circular wedge that are arranged to operate synchronously as the spindle rotates. The stacked rimmed containers can be placed in a rack, which can be inverted and placed against the rotation cylinders. As the at least one spindle rotates the rims of the containers engage with the thread of the screw-toothed cylinder, which carries the containers downward towards the semi-circular wedge. As the containers pass the rotating semi-circular wedge, the narrow end of the wedge inserts between the rims of two adjacent containers and gradually separates the containers to the bottom container can fall off the stack of containers in an upright position.