Abstract: A non-radiative dielectric waveguide coupler for coupling or dividing high-frequency signals between at least two dielectric waveguides arranged maintaining a predetermined gap between a pair of parallel flat conductors, wherein said two dielectric waveguides are connected to each other through a bridge of a dielectric material. Upon joining the two dielectric waveguides through the bridge, the gap between the two dielectric waveguides, that affects the characteristics of the coupler, is set maintaining a high precision without effecting any particular positioning operation. Therefore, the coupler can be mass-produced very favorably. Besides, the gap between the two dielectric waveguides is stably maintained without being varied during the production of the coupler or during the use of the coupler, contributing to improving the reliability of the coupler.