A light source apparatus 3 has a lighting time period measuring section (steps S3, S4, S6 and S7) measuring lighting time periods of respective LEDs, a junction temperature calculating section (steps S5 and S8) that calculates junction temperatures of the respective LEDs, a light intensity deterioration characteristic storing section storing light intensity deterioration characteristics based on the junction temperatures of the respective LEDs, a light source drive characteristic storing section storing characteristics of power that drives the respective LEDs and light intensities, a deteriorated light intensity calculating section (steps S12 and S 14) calculating deteriorated light intensities based on the measured lighting time periods, the calculated junction temperatures, and the light intensity deterioration characteristics stored in the light intensity deterioration characteristic storing section, and a light source power control section (steps S12 and S 14) controlling power that drives the light sources, based on the deteriorated light intensities calculated by the deteriorated light intensity calculating section, and the characteristics stored in the light source drive characteristic storing section.
