A variable nozzle turbocharger for changing a flow speed of exhaust gas to be blown to a turbine wheel, the variable nozzle turbocharger comprising: a main plate; a unison ring; variable nozzles configured such that their opening degrees are changed along with rotation of the unison ring, wherein: a first facing surface of the unison ring is opposed to a second facing surface of the main plate via a gap; and the first facing surface is provided with a plurality of first projections projecting toward the second facing surface and placed at intervals along a circumferential direction of the unison ring, the unison ring is aligned with the main plate in a thickness direction of the main plate; characterised in that the first facing surface includes a plurality of first recessed portions placed at intervals in the circumferential direction of the unison ring, the plurality of first projections and the plurality of first recessed portions are alternately arranged on the first facing surface along with the circumferential direction of the unison ring; and the second facing surface includes a plurality of second recessed portions placed at intervals in the circumferential direction of the main plate, wherein the second facing surface includes a plurality of second projections placed at intervals in the circumferential direction of the main plate; the plurality of second projections and the plurality of second recessed portions are alternately arranged on the second facing surface along with the circumferential direction of the main plate; the plurality of first projections provided on the first facing surface is inserted into the plurality of second recessed portions; and the plurality of second projections is inserted into the plurality of first recessed portions. a main plate; a unison ring; variable nozzles configured such that their opening degrees are changed along with rotation of the unison ring, wherein: a first facing surface of the unison ring is opposed to a second facing surface of the main plate via a gap; and the first facing surface is provided with a plurality of first projections projecting toward the second facing surface and placed at intervals along a circumferential direction of the unison ring, the unison ring is aligned with the main plate in a thickness direction of the main plate; characterised in that the first facing surface includes a plurality of first recessed portions placed at intervals in the circumferential direction of the unison ring, the plurality of first projections and the plurality of first recessed portions are alternately arranged on the first facing surface along with the circumferential direction of the unison ring; and the second facing surface includes a plurality of second recessed portions placed at intervals in the circumferential direction of the main plate, wherein the second facing surface includes a plurality of second projections placed at intervals in the circumferential direction of the main plate; the plurality of second projections and the plurality of second recessed portions are alternately arranged on the second facing surface along with the circumferential direction of the main plate; the plurality of first projections provided on the first facing surface is inserted into the plurality of second recessed portions; and the plurality of second projections is inserted into the plurality of first recessed portions. a first facing surface of the unison ring is opposed to a second facing surface of the main plate via a gap; and the first facing surface is provided with a plurality of first projections projecting toward the second facing surface and placed at intervals along a circumferential direction of the unison ring, the unison ring is aligned with the main plate in a thickness direction of the main plate; characterised in that the first facing surface includes a plurality of first recessed portions placed at intervals in the circumferential direction of the unison ring, the plurality of first projections and the plurality of first recessed portions are alternately arranged on the first facing surface along with the circumferential direction of the unison ring; and the second facing surface includes a plurality of second recessed portions placed at intervals in the circumferential direction of the main plate, wherein the second facing surface includes a plurality of second projections placed at intervals in the circumferential direction of the main plate; the plurality of second projections and the plurality of second recessed portions are alternately arranged on the second facing surface along with the circumferential direction of the main plate; the plurality of first projections provided on the first facing surface is inserted into the plurality of second recessed portions; and the plurality of second projections is inserted into the plurality of first recessed portions.