An endoscope illumination apparatus includes a light convertor including first and second light conversion members that receive primary light emitted from a primary light source and convert at least one of the optical properties of the primary light, a detector that receives at least part of first light conversion light converted by the first light conversion member as detection light, and outputs a detection signal corresponding to a quantity of the detection light, and an operation estimation circuit that estimates, based on an amount of change in the detection signal output from the detector, whether any one of the first and second light conversion members is in an abnormal operation or both of the first and second light conversion members are in an abnormal operation.
