PURPOSE: The titled cooler providing highly steamed tea leaves having a small amount of cut leaves and powder, by steaming raw leaves slightly lightly by the process of a steamer, irradiating them with a near ultraviolet light heater at the highest step of the cooler equipped with plural steps of endless conveyor belts.

CONSTITUTION: Raw leaves of the first tea of middle period is steamed slightly lightly by the steamer 16, and dropped on the starting end part 4 of the first step 1 of endless conveyor belt of a cooler equipped with a device for adjusting degree of steam in such a way that the leaves are spread uniformly and thinly on it. The leaves are passed below the near ultraviolet light heater 5 and heated efficiently and uniformly to the interior to promote degree of steaming. When the highly steamed leaves are dropped on the net belt of the second step 2, they are quenched with cold air from the blower 6, and further cooled with cold air from the blower 7 at the third step 3.