PURPOSE: To obtain an extended X-ray absorption fine structure (EXAFS) measuring instrument which can use liquid samples as objects to be measured.

CONSTITUTION: The instrument is constituted in such a way that X-rays of different energy are taken out by changing the incident angle θ of X rays R1 made incident to a monochromator 10 from an X-ray source F while the source F, monochromator 10, and a light receiving slit 17 are always positioned on a Rowland circle L1 and the X rays are projected upon a sample 27. The circle L1 is set so that the circuit L1 can be included in a vertical plane and the sample 27 is supported by means of a cylindrical sample holder 53. In addition, the holder 53 is maintained so that the holder 53 can be parallel-displaced by means of a horizontal sample holding mechanism 62 without being tilted.