A plurality of LEDs are arrayed in the X-direction, and a light-guide plate is provided facing the LEDs. A plurality of prisms extending in the Y-direction are formed on a light-receiving surface of the light-guide plate. A plurality of prisms are additionally formed on a light-emitting surface of the light-guide plate. Light emitted from the LED is thereby divided into a plurality of light beams by the prisms, and a portion of the light is condensed toward the prisms. Light that is condensed toward the prisms is divided in a plurality of directions and transmitted in the light-guide plate. When the light reaches another prism, the light is reflected by the prism and emitted from the light emitting surface.