Wavelength-multiple optical recording medium

A wavelength-multiple optical memory is provided which is capable of performing high density recording/reading at room temperature. A large number of cylindrical recording members, each of which is made up of plural portions along a central axis of the cylinder and plural sizes which vary slightly in a direction perpendicular to the central axis, are formed on a substrate. The cylindrical recording members may be of circular cylindrical or elliptical cylindrical shape. It is preferable that recording material layers of the cylindrical recording members have complex refractive indexes which are different from each other. A difference in size of the recording material layers of the circular or elliptical cylinders having sizes closest to each other is preferably in a range of 1/5000 to 1/5 of an average of the sizes, are even more preferably in a range of 1/500 to 1/10. Wavelength-multiple recording is performed by changing a wavelength of a light beam emitted from a light source within a very narrow range.