An excellent method of cleaning a textile product capable of removing oligomers, the residue of dyes, and the like completely (or substantially completely) without causing insufficient cleaning or overcleaning by employing a treating apparatus of a type which treats a textile product by circulating a treating liquid. The cleaning method comprises a high temperature treating step of treating a textile product placed in a treating bath by bringing a textile product into contact with a treating liquid circulating through the treating bath while heating the treating liquid to high temperature by means of an indirect heat exchanger provided at a portion of the circulation path, and a liquid replacing/cleaning step of supplying cleaning water gradually into the treating bath while discharging the high-temperature treating liquid gradually therefrom and lowering the liquid temperature in the treating bath down to a predetermined point while keeping the quantity of liquid in the treating bathconstant by exchanging heat directly between the high-temperature treating liquid being discharged and the cleaning liquid being supplied and equalizing the quantity of high-temperature treating liquid being discharged to the quantity of cleaning liquid being supplied. An optimal value of the temperature gradient in the liquid replacing/cleaning step is preset and the actual temperature gradient is equalized or approximated to the optimal value by performing heating or cleaning through the indirect heat exchanger.