To provide a new method for continuously relaxing a fiber structure by which the rubbing effects on a fabric are great and performances such as crimping, a shrinkage difference and untwisting torque of a yarn can be exhibited with remarkably improved productivity in the same manner as that of treatment with a liquid jet treating machine or a rotary washer treating machine.

This method for continuously relaxing the fiber structure comprises taking out the fiber structure during running once from a treating liquid, then making the fiber structure collide with the surface of the treating liquid or a plate surface again and thereby applying shocks to the fiber structure when the polyalkylene terephthalate fiber structure is run in the treating liquid and continuous relaxing treatment is thereby carried out.