<p>An image forming apparatus having a main body (1) includes an opening portion (20) provided in the side face (1a) of the main body (1), and a thermal transfer printer (2). The thermal transfer printer (2) records desired information additively on a paper whereon a fixing means (17) has fixed a toner image, by using a thermal head (5) to pressure an ink-ribbon (41) on said paper. The thermal transfer printer (2) includes a casing (3) wherein a cassette (4) for housing the ink-ribbon (41) is detachably mounted, a thermal head supporting means (60) for supporting the thermal head (5) and an interlocking mechanism (8). The interlocking mechanism (8) retreats the thermal head (5) by the thermal head supporting means (60) in response to retreat of said casing (3). Thus it is allowed to detach the cassette (4) from the main body (1) through the opening portion (20). It facilitates replacement of cassettes (4) and jam recovery.</p>
