A light source installation in back light unit to effectively shorten the area required for incorporation of wavelength from each of multiple LEDs is comprised of multiple LED units; each LED unit being comprised of multiple LEDs; multiple LED units being disposed on a locking member and each LED unit being disposed on a curved section formed by the locking member and further on the incident plane of the light guide plate in different directions; and light emitted from those multiple LED units being mixed to incorporate wave length from each LED into white light.