Light spot advancing direction judging device and method, optical head control device and method, and optical disk recording/reproducing device

A device and a method can judge the radial moving direction of light spots formed on the signal recording surface of an optical disc having grooves of two types that are different from each other in terms of depth and arranged along a recording track that is a land of the optical disc. The judging section of the device judges the moving direction of the main spot on the basis of binarized data of a difference signal of the main spot and binarized data of a difference signal of one of the side spots. With this arrangement, the moving direction of the light spots relative to a radial direction of the optical disc can be determined only by using difference signals without using any sum signal.