An annular oblique light illumination apparatus manufactured by using a flexible wiring substrate in which a plurality of arcuate zonal wiring patterns each in the form of a developed frustconical shape as a light emitting device arranging surface when cut along the pattern are serpiginously formed continuously to a base film of a predetermined shape, by setting and soldering light emitting devices to the arcuate zonal wiring patterns, cutting out the arcuate zonal wiring patterns to form light emitting device arrays and fixing the same to the arranging surface, whereby the wiring substrate can be supported reliably without using any special jig conforming the arcuate shape of the wiring patterns for mounting the light emitting devices, thereby improving the soldering operation efficiency, saving the troubles of exchange and handling of jigs and further, avoiding slackening or distortion of the wiring substrate even in a case of applying soldering by a flow soldering apparatus.