PURPOSE: To prevent erroneous execution of printing by a system wherein a control means controls a changer so as not to remove and mount an ink ribbon cassette on a stocker when a stocker condition detection means detects that the stocker is in a predetermined position.

CONSTITUTION: A control means 105 controls a changer 103 so as to remove an ink ribbon cassette being held at an optional position of a stocker 102 and mount it on a carriage 101, or to remove the ink ribbon cassette being held by the carriage 101 and mount it in an optional vacant position of the stocker 102. Here, when a stocker condition detection means 106 detects that the stocker 102 is not in a predetermined condition where exchanging of the ink ribbon cassette by a user is possible, the control means 105 controls the changer 103 so as not to remove nor mount the ink ribbon cassette based on the detected information.