Method for determining deterioration of led light source, deterioration determination system, and computer program

In this method for determining deterioration of an LED light source including a plurality of LED elements, the current and voltage supplied to the LED light source for the purpose of lighting the plurality of LED elements are measured, the temperature is measured by a temperature sensor provided to the LED light source, the measured current and voltage and a history of temperatures measured by the temperature sensor are used as a basis to calculate a representative value for the junction temperature of the plurality of LED elements at the time of lighting, and the deterioration state of the LED light source is determined on the basis of the relationship between the representative value and the lighting time of the plurality of LED elements.