A backlight device 13 includes LEDs 22, a light guide plate 24, and a light reflecting portion 34. The light guide plate 24 is a plate member and includes a light entrance surface 24a, an opposite edge surface 24d, and a light exit surface 24b. The light entrance surface 24a is an edge surface of the plate member and opposite the LEDs 22 and light emitted by the LEDs 22 enters the light guide plate 24 through the light entrance surface. The opposite edge surface 24d is another edge surface of the plate member that is on an opposite side from the light entrance surface 24a. The light exit surface 24b is a plate surface of the plate member and the light entering through the light entrance surface 24a exits the light guide plate 24 through the light exit surface. The light reflecting portion 34 is disposed on at least the opposite edge surface 24d and reflecting light travelling within the light guide plate 24 toward the opposite edge surface 24d.