PURPOSE: To reduce the wearing of a storage medium and a reading device by arranging information inside the storage medium three-dimensionally and reading all bits of information on the cross section of the storage medium during one rotation of the storage medium.

CONSTITUTION: This three-dimensional storage device is constituted by combining a storage medium 2 with the pick-up 2 of the reading device. Laser is emitted from the light emitting part 3 of the pick-up 2 and the intensity of a transmitted light is measured at a light receiving part 4. A storage medium 1 is rotated once around a rotary shaft 5 while measuring. All bits of information gained during one rotation is processed by computer and how a small face having low transmissivity is arranged on the cross sectional is restored. When the pick-up 2 of the reading device is moved in parallel with the rotary shaft 5, another cross section is read.