A printer system includes an ink ribbon end detector for detecting that the ink ribbon cassette has been used to the end; an used ink ribbon cassette holding position memory device for storing therein information indicative of holding position of a used ink ribbon cassette held on a stocker when the ink ribbon cassette end detection means detects that an ink ribbon has been used to the end, and a cassette holding determining device for determining whether or not an ink ribbon cassette whose ink ribbon has not been used is set in the stocker based on holding information. In the printer system having the described arrangement, an optimal available ink ribbon cassette is selected, and in the case of storing plural ink ribbon cassettes in the same color, a continuous printing operation of a large capacity may be performed without using user's hands.