PURPOSE: To enable the automatic and time-saved measurement of yarn crimp properties by calculating them, particularly crimp number and percentage crimp, on the basis of the data detected by scanning the test yarns fixed on a paste board in lengthwise and widthwise directions as well as the pattern data.

CONSTITUTION: Pressure sensitive adhesive double coated tapes are adhered to both ends of a paste board sheet. A test yarn is adhered to one tape on one end, then the other end of the yarn is sucked to give a certain tension and adhered to the other tape so that the yarn is fixed on the paste board under an initial load. Main scanning is performed on the test yarn in the lengthwise and widthwise directions and simultaneously subscanning is effected in the lengthwise direction and the pattern data is inputted to the reader. The change in coordinate data is detected based on the pattern data input and the maxima and minima are detected from the detected data. The number of crimp is calculated from at least one of the maxima and the minima. The percentage of crimp is calculated based on the detected data on the yarn length from the subscanning.