An X-ray analysis assistance device with an input and operation device 24 for arbitrarily inputting and setting the value of one from among the distance L between a sample S and a two-dimensional detector 2 and the maximum detection range Xmax for X-rays scattered or diffracted by the sample S, and a central processing unit 20 for automatically setting the other setting item on the basis of the value of the one setting item set by the input and operation device 24. Further, the maximum measurement frame Hmax for the X-rays is displayed on a display screen 22 of a display device 21 on the basis of the distance L and maximum detection range Xmax. Additionally, an X-ray detection area A indicating the range within which it is possible for the detection surface of the two-dimensional detector 2 to detect X-rays is displayed on the display screen 22 of the display device 21.