An illuminating device includes: a solid-state light emitting element that includes a light source and a phosphor and emits light from the light source and phosphorescent light emitted from the phosphor excited with the light from the light source toward an optical system; and a reflective portion that reflects part of the light emitted from the solid-state light emitting element, which does not enter the optical system, back to the solid-state light emitting element so that the reflected light having originated from the light source is used to excite the phosphor.