Electronic device comprising recording and reproducing unit

An electronic device capable of removably mounting a recording and reproducing unit such as a hard disk drive and the like is provided, while giving consideration to sound proofing measures in the device. A structure is provided such that: an opening portion 7 is formed at a bottom face side of a chassis 4 ; a bottom plate 3 which covers the opening portion 7 is mounted on a hard disk unit 8 in which a hard disk drive 10 and a control board 11 are integrated with each other; and the hard disk unit 8 is mounted on or removed from the opening portion 7 ; and a shield member 6 and/or a sound proof member for covering the hard disk unit 8 are/is mounted on a top face side of the opening portion 7.