Uneven brightness is less likely to occur in a backlight unit. In a backlight unit 12, suppose that a maximum value and a minimum value of light reflectance of at least a first surface 30a of a diffuser plate 30 facing a hot cathode tube 17 are defined as Rmax Rmin, respectively, a rising proximal position BP of each rising portion 20b of a reflection sheet 20 is provided to overlap with an area of the diffuser plate 30 having light reflectance R that satisfies the Expression given below, and a rising distal position EP of each rising portion 20b is provided not to overlap with an area of the diffuser plate 30 having the light reflectance R that satisfies the Expression given below. (Rmax−Rmin)/2+Rmin