Abstract: A tilt detector for detecting a tilt amount of a recording surface of an optical disc at a high degree of precision. The tilt detector comprises a light emitting diode for emitting a divergent beam of light to be incident on the recording surface of the optical disc, a collimating lens for collimating the divergent beam of light emitted from the light emitting diode and directing the collimated beam of light onto the recording surface of the optical disc, a condensing lens for condensing the collimated beam of light from the collimating lens, directed onto the recording surface of the optical disc and then reflected from the recording surface, and a photodiode for receiving the collimated beam of light condensed by the condensing lens and detecting the centroid of the intensity of the received beam of light, the photodiode including a receiving surface partitioned into a plurality of areas for receiving the collimated beam of light condensed by the condensing lens.