PURPOSE: To enable ribbon cassettes to be exchanged easily by one-action attaching and detaching operations for a printer by coupling the pin of a table with a slant line shaped notch provided on both sides of the ribbon case.

CONSTITUTION: When a ribbon cassette 18 is pushed into the upside of a table 34 above a spring part 35, the table 34 moves toward a ribbon sending roller 11 side on the locus of a pin 33 moving along a notch 32 provided on both sides of the ribbon case 31 and is set. Since the end of the notch 32 is designed to cause the pin 33 to drop into it, the table 34 is locked by dropping of the pin 33. When exchanging the ribbon, when the ribbon cassette 18 locked is slightly pushed in, the cassette 18 is slightly lifted up along the notch 33 due to unlocking, and therefore, the cassette 18 can be easily taken out.