PURPOSE: To provide a quality controlling apparatus for a draw false-twister capable of getting the data for tension control, the data for yarn evaluation and the data for the inspection of the false-twisting unit at respective optimum time intervals.

CONSTITUTION: This quality controlling apparatus is provided with a sampling means 15 for sampling measured tension data at a prescribed time interval (t), a memory 20 for separately storing at least the sampled tension data S, the mean value (m1) of the n1 tension data and the mean value (m2) of the n2 tension data, an evaluation means 17 for evaluating the tension data and generating an alarm when the evaluation result is out of a control limit, a controlling means 18 for controlling the tension according to the mean value (m1) and a transmission means 16 for transmitting the mean value (m2) to an upper surveillance apparatus 13.