PURPOSE: To prevent occurrence of faults such unevenness of dyeing or ruggedness by heating and controlling the temperature of the outer wall surfaces of the whole or important parts of a circulatory treatment passage of a rope-shaped textile product to a temperature equal to or somewhat higher than the treatment temperature and preventing dew condensation.

CONSTITUTION: In an air-current type treatment apparatus for circulating and treating a rope-shaped textile product of a fabric, etc., the outer wall surfaces of the whole body or important parts such as a header 2 and a residential tank 6 of a circulatory treatment passage 1 composed of the header unit 2 involving a drive reel or roll 3 incorporated therein, a transfer pipe 5 having a treatment fluid injection part 4 and a residential tank 6 are covered, e.g. with a coil-shaped electric heater 15 or a jacket capable of supplying steam or another heating medium so at to heat it through a control circuit to a temperature equal to or somewhat higher than the treatment temperature in the passage 1. Dew condensation on the inner surfaces of the circulatory treatment passage 1 can be prevented during the course of a circulatory treatment, e.g. dyeing of a rope-shaped textile product 7 and occurrence of, e.g. unevenness of dyeing or ruggedness caused by dropping of the dew can, therefore, be prevented.