Buffer materials 7 and a lower principal surface 6a of a hard disk case 6, and the buffer materials 7 and a hard disk drive 5, are adhesively fixed to each other by strong pressure-sensitive adhesive forces. Pressure-sensitive adhesive materials 8 are provided between the hard disk drive 5 and an upper principal surface 6b of the hard disk case 6. The pressure-sensitive adhesive force of each pressure-sensitive adhesive material 8 is weak to such a degree that the pressure-sensitive adhesive material 8 becomes detached by a contraction force of each buffer material 7. Thus, when external disturbance is applied to the hard disk drive 5, each pressure-sensitive adhesive material 8 becomes detached during contraction of each buffer material 7. The contraction of each buffer material 7 and the detachment of each pressure-sensitive adhesive material 8 allow improvement of the impact resistance of the hard disk drive 5.