The X-ray reflecting intensities from a number of net planes of the Rochelle salt are measured in some detail by means of the double crystal ionization spectrometer at a temperature range 15°-30°C including the upper Curie point (ca. 24°C). As a result, the existence of a definite temperature effect on the reflecting intensity has been infallibly confirmed and it is concluded that this effect is to be explained as due to the variation of the secondary structure of this crystal in the neighbourhood of its Curie point, but not due to the change in the structure factor as formerly stated by Staub. Also, it is painted out that the assumption of the existence if the spontaneously polarized and spontaneously deformed domains in the Rochelle salt crystal is a highly plausible one