A connector-attached dielectric waveguide comprising a dielectric waveguide and a connector, the dielectric waveguide including a dielectric waveguide body and a dielectric waveguide end, the dielectric waveguide end having a smaller cross-sectional area than the dielectric waveguide body, wherein the connector comprises: a connecting portion that is connectable with an opposite component and that slidably holds the dielectric waveguide body; and a fixing portion that is axially movably connected with the connecting portion and that is fixed to the dielectric waveguide body, wherein the fixing portion includes at a first end an internal thread that engages with an external thread formed on the connecting portion to form an axially movable connection with the connecting portion, wherein the fixing portion includes a fitting hole into which the dielectric waveguide body is fit, characterized in that the fixing portion further includes at a second end a tapered surface whose outer diameter decreases toward the second end, and the tapered surface includes a clamp that is configured to thrust in the direction of the internal thread to press the inner surface of the fitting hole in the direction of reducing the diameter of the fitting hole. the dielectric waveguide including a dielectric waveguide body and a dielectric waveguide end, the dielectric waveguide end having a smaller cross-sectional area than the dielectric waveguide body, wherein the connector comprises: a connecting portion that is connectable with an opposite component and that slidably holds the dielectric waveguide body; and a fixing portion that is axially movably connected with the connecting portion and that is fixed to the dielectric waveguide body, wherein the fixing portion includes at a first end an internal thread that engages with an external thread formed on the connecting portion to form an axially movable connection with the connecting portion, wherein the fixing portion includes a fitting hole into which the dielectric waveguide body is fit, characterized in that the fixing portion further includes at a second end a tapered surface whose outer diameter decreases toward the second end, and the tapered surface includes a clamp that is configured to thrust in the direction of the internal thread to press the inner surface of the fitting hole in the direction of reducing the diameter of the fitting hole. a connecting portion that is connectable with an opposite component and that slidably holds the dielectric waveguide body; and a fixing portion that is axially movably connected with the connecting portion and that is fixed to the dielectric waveguide body, wherein the fixing portion includes at a first end an internal thread that engages with an external thread formed on the connecting portion to form an axially movable connection with the connecting portion, wherein the fixing portion includes a fitting hole into which the dielectric waveguide body is fit, characterized in that the fixing portion further includes at a second end a tapered surface whose outer diameter decreases toward the second end, and the tapered surface includes a clamp that is configured to thrust in the direction of the internal thread to press the inner surface of the fitting hole in the direction of reducing the diameter of the fitting hole.