PROBLEM TO BE SOLVED: To provide an inspection system for endoscope light guide which is used for inspecting the spectral deterioration of a light guide.SOLUTION: An endoscope processor 20 includes a memory 23, a system controller 24, and a color difference computing circuit 27. When initialization of the light guide is carried out, the color difference computing circuit 27 generates an initial color coordinate component from an initial image signal. The memory 23 stores the initial color coordinate component. When a light guide inspecting function is carried out, the color difference computing circuit 27 generates an inspection color coordinate component from an inspection image signal. The color difference computing circuit 27 computes a color difference from the initial color coordinate component and the inspection color coordinate component. The system controller 24 compares the color difference with first and second thresholds to discriminate whether the spectral deterioration has occurred to the light guide 31.
