Since an information processing unit of the present invention includes a protrusion portion on a back face side of a first casing, it is possible to reduce an impact transmitted to a notebook PC when the notebook PC is placed in an upright position on the surface of a desk. Therefore, it is possible to prevent the notebook PC from being damaged. Furthermore, since the protrusion portion is provided to the back face side of the first casing, it is possible not to allow the notebook PC to stand self-supported in an upright position. Therefore, the notebook PC will not be placed carelessly in an upright position on the surface of a desk or the like; thus, it is possible to prevent the PC from being broken or damaged due to a fall.