Combustor and gas turbine

A combustor comprising:

• a pilot nozzle;
• a plurality of main nozzles arranged apart from the pilot nozzle in a circumferential direction on an outer peripheral side of the pilot nozzle and configured to perform premix combustion;
• a combustor basket surrounding the pilot nozzle and each main nozzle;
• a ring provided at a tip end of the combustor basket;
• and
• a combustion liner, an inner surface of which is fitted onto an outer periphery of the combustor basket and surrounds the ring,
• wherein the ring is formed such that an inner wall surface thereof is parallel to an inner wall surface of the combustion liner, or is formed such that an inner diameter thereof decreases toward a downstream side of a flow of premixed gas,
• wherein an outer diameter of the ring decreases toward an end portion of the ring, the end portion located at the downstream side of the flow of the premixed gas.