A deck chassis assembly for a magnetic recording/reproducing apparatus, in which some parts may be sub-assembled for independent operation, comprises a base chassis mounting a moving deck therein. The base chassis includes integrally formed sidewalls at opposite sides thereof to mount and receive the moving deck. A housing chassis has sidewalls of which opposite ends are rotatably connected to ends of the sidewalls of the base chassis, and a link member is interposed between the housing chassis and the base chassis to enable the housing chassis to rotate a predetermined angle relative to the base chassis in an opening and closing manner.