An encoding device for encoding a bit stream including an image frame may include an encoder configured to determine a position of a pixel having a last non-zero coefficient in a conversion coefficient block constituting the image frame with reference to a predetermined pixel of the conversion coefficient block, identify a sub-block including the last non-zero coefficient, among a plurality of sub-blocks constituting the conversion coefficient block, convert a position of the last non-zero coefficient determined with reference to the predetermined pixel of the conversion coefficient block into a position with reference to a predetermined pixel of the identified sub-block, and encode the sub-block including the last non-zero coefficient and the converted position of the last non-zero coefficient.