A magnetic tape recording/reproducing apparatus is disclosed that selectively loads a first tape cassette accommodating a first magnetic tape or a second tape cassette accommodating a second magnetic tape having a width greater than the width of the first tape. The apparatus includes a rotating drum unit including a lower stationary drum and an upper rotating drum, and a loading mechanism that, if the first tape cassette is loaded, pulls the first magnetic tape out of the first tape cassette and winds it onto the rotating drum unit through a first winding angle so as to form a first tape path and, if the second tape cassette is loaded, pulls the second magnetic tape out of the second tape cassette and winds it onto the rotating drum unit through a second winding angle greater than the first winding angle so as to form a second tape path.