Abstract: A linear light source device comprises a wiring substrate in a rectangular shape and having a wiring pattern formed thereon, a plurality of light emitting elements arranged on the wiring substrate in a longitudinal direction of the wiring substrate and connected with the wiring pattern on the wiring substrate, and a sealing resin that seals the light emitting elements, wherein the linear light source device is to be arranged on a side surface of a light guiding plate to form a planar light source device, and an external connection terminal is arranged on a surface of the wiring substrate that is opposite to a surface of the wiring substrate where the light emitting element are arranged and in a central portion in the longitudinal direction of the wiring substrate, and connected with the wiring pattern.