PURPOSE: To remarkably save the processing cost or processing time and simply improve the hand of a textile product or dye the textile product at a low cost without polluting a regional environment or a working environment.

CONSTITUTION: Either or both of a microorganism capable of producing a natural product such as an enzyme modifying a textile product and a microorganism capable of producing a coloring matter capable of dyeing the textile product are prepared and then inoculated into a culture medium capable of proliferating the prepared microorganism. The textile product is subsequently immersed in the culture medium before or after the inoculation to culture and proliferate the microorganism in the culture medium. Thereby, the natural product or coloring matter is produced. The textile product is then subjected to processing treatment with a culture solution containing a microorganism in a proliferated state or a resting state thereof. This apparatus for processing is equipped with a culture solution storage part 12, installed in the interior of a pressure-resistant vessel 10 and used for storing the culture medium or culture solution 11, a textile product transfer part 14 for transferring the textile product 13 in the culture medium or culture solution and a culture solution temperature regulator 15 for maintaining the culture medium or the culture solution 11 at a prescribed temperature.