Abstract: An ID card printer with a manual card slot in which supplying of the cards to be printed into a printing unit is classified into an automatically supplying mode in which the cards to be printed are sequentially in an automatic way supplied from the conventional card hopper and a manually supplying mode in which the cards to be printed are manually supplied from a manual card slot one by one; the cards to be printed are selectively inserted into the printing unit based on the user's selections between the two modes depending on the priority of the printing event in question or current printing speed; and, the printed cards in the automatically supplying mode and the printed cards in the manually supplying mode are not mixed with each other but are collected back in a discrete manner, whereby improving efficiency of card printing operations.