A light source device with arrayed light emitting elements includes a base board on which a plurality of the light emitting elements are arranged in an array, a convergent rod lens provided parallel to the array of the light emitting elements, and a reflection casing for holding the convergent lens. The convergent lens and the reflection casing are integrally connected with an air-gap formed parallel to the cnvergent lens. The base board is secured upon being inserted into the air-gap. The convergent lens and reflection casing in the light source device with arrayed light emitting elements can integrally and simultaneously be molded by continuous two-color extrusion molding. Therefore, it is possible to manufacture the light source device with arrayed light emitting elements at lower cost and which can easily be assembly with a reduced number of parts.