An illumination device includes: a light emitting element to be a light source; a light amount detecting means for detecting the amount of light emitted by the light emitting element; a light emitting element drive means for controlling drive current supplied to the light emitting element so that the difference between the light mount detected by the light amount detecting means and a light amount target value becomes small; a junction temperature detecting means for calculating junction temperature of the light emitting element; and a setting means for setting the light amount target value in accordance with the junction temperature detected by the junction temperature detecting means.