A recording/reproducing device which is thinner when it is loaded with and without a cartridge, except while a cartridge is being inserted or taken out. A first cabinet (2) incorporates recording/reproducing means and has an opened top. A second cabinet (1) is so connected to the first cabinet (2) as to close the opening of the first cabinet (2). The second cabinet is so fitted in the first cabinet (2) as to sink in the thickness of the first cabinet (2) as shown in FIG. 1(b) when a cartridge (7) is loaded and not loaded therein, except while the cartridge (7) is being inserted or taken out. While the cartridge (7) is inserted or taken out, the second cabinet (1) is separated by a distance d from the first cabinet (2) as shown in FIG. 1(a), thereby defining an opening through which the cartridge (7) is inserted/taken out.