A high-pressure vessel for a vehicle, the high-pressure vessel comprising: a plastic liner including a through hole provided thereon; a plastic sealing member , a portion of which is positioned in the through hole and a remaining portion of which overlaps with the plastic liner , wherein the portion overlapping with the plastic liner is combined with the plastic liner by thermal bonding; a metallic nozzle boss combined with the plastic sealing member so as to cover the portion of the plastic sealing member overlapping with the plastic liner ; and a composite material layer combined with the plastic liner and the metallic nozzle boss so as to cover the plastic liner and the metallic nozzle boss ; the high-pressure vessel for a vehicle wherein the plastic sealing member includes a cylindrical part positioned in the through hole of the plastic liner and protruding in an outer side direction of the plastic liner , and a wing part of a circular plate shape provided to bend so as to correspond a shape of the plastic liner while extending in a radial direction from an end of the cylindrical part and a predetermined section of which is combined with an outer surface of the plastic liner by the thermal bonding; wherein the metallic nozzle boss is screwed to the plastic sealing member (M1); and characterised in that a major portion of a lower surface of the metallic nozzle boss , which faces the plastic liner , is in contact with the plastic sealing member and only some portion thereof is in contact with the plastic liner . a plastic liner including a through hole provided thereon; a plastic sealing member , a portion of which is positioned in the through hole and a remaining portion of which overlaps with the plastic liner , wherein the portion overlapping with the plastic liner is combined with the plastic liner by thermal bonding; a metallic nozzle boss combined with the plastic sealing member so as to cover the portion of the plastic sealing member overlapping with the plastic liner ; and a composite material layer combined with the plastic liner and the metallic nozzle boss so as to cover the plastic liner and the metallic nozzle boss ; the high-pressure vessel for a vehicle wherein the plastic sealing member includes a cylindrical part positioned in the through hole of the plastic liner and protruding in an outer side direction of the plastic liner , and a wing part of a circular plate shape provided to bend so as to correspond a shape of the plastic liner while extending in a radial direction from an end of the cylindrical part and a predetermined section of which is combined with an outer surface of the plastic liner by the thermal bonding; wherein the metallic nozzle boss is screwed to the plastic sealing member (M1); and characterised in that a major portion of a lower surface of the metallic nozzle boss , which faces the plastic liner , is in contact with the plastic sealing member and only some portion thereof is in contact with the plastic liner . the plastic sealing member includes a cylindrical part positioned in the through hole of the plastic liner and protruding in an outer side direction of the plastic liner , and a wing part of a circular plate shape provided to bend so as to correspond a shape of the plastic liner while extending in a radial direction from an end of the cylindrical part and a predetermined section of which is combined with an outer surface of the plastic liner by the thermal bonding; wherein the metallic nozzle boss is screwed to the plastic sealing member (M1); and characterised in that a major portion of a lower surface of the metallic nozzle boss , which faces the plastic liner , is in contact with the plastic sealing member and only some portion thereof is in contact with the plastic liner . <EOS>