Abstract: A magnetic tape cassette having a pair of spaced-apart reels rotatably mounted on a support wall. A length of tape has its opposite ends secured respectively to the two reels and its intermediate portion wound around the reels to form corresponding tape rolls whose diameters vary inversely as the tape is simultaneously unwound from one reel and wound onto the other. The two rolls have outer tape windings with recording surfaces thereon facing each other. Tape cleaning means is interposed between, and biased into contact with, the outer winding facing surfaces for continuously cleaning those surfaces as the tape is unwound from one reel and wound onto the other.