PURPOSE: To enable to fit and detach a correction ribbon without disassembling a cassette casing, by a method wherein a supplying reel and a take-up reel for supporting a correction ribbon are provided, and two supporting plates are coupled to each other on the inside of a ribbon passage to constitute a cassette casing.

CONSTITUTION: The correction ribbon 6 is minutely fed by driving the take-up reel 8 by a pulse motor 38, is pressed by a leaf spring 23a, an teeth 11 of the supplying and take-up reels 7, 8 are engaged to pawls 20 of a detent 17, whereby the reels are prevented from idling, the ribbon 6 is prevented from sagging, and is provided with an appropriate tension. When the ribbon 6 is completely taken up by the reel 8, both the reels 7, 8 are detached from notches 5 of the supporting plate 2 by bending bases 19 of a reel presser 15, and a fresh ribbon 6 can be easily fitted into the notches 5 in a single-stroke manner without disassembling the cassette casing 1. Accordingly, the correction ribbon can be easily fitted and detached without disassembling the cassette casing and without discarding the casing together with the used ribbon.