A backlight device of the present invention includes a substrate (2), a liquid crystal layer (4), and a scattering layer (5). The substrate (2) has a surface facing the liquid crystal layer (4), on which surface two comb electrodes (3a and 3b) are provided. The comb electrode (3a) includes a plurality of comb-teeth parts (33a) meshing with a plurality of comb-teeth parts (33b) of the comb electrode (3b). Therefore, the comb electrodes (3a and 3b) can causes electric fields to be generated, in response to an applied voltage, in at least two directions each parallel to the surface of the substrate (2). Further, there is a region whose effective refractive indexes with respect to polarized light p and polarized light s become large. It is therefore possible to control emission of both the polarized light p and the polarized light s.