Abstract: A cup lid for easy discharge of internal gas which seals the upper portion of the cup body and discharges the internal gas of the cup body to the outside as the internal gas pressure of the cup body increases. The cup lid includes a cover portion that is detachably coupled to an upper portion of the cup body and has a circulation groove formed at one end thereof; a seal that protrudes from the lower end of the cover portion and is coupled to the upper end of the cup body; and an outlet that is coupled to the circulation groove for discharging the gas inside the cup body to the outside.