With the use of the sample cell, it is possible to control the thickness of a fluid sample to be analyzed. The sample cell includes a sample cell outer frame 107 having openings at both ends, a lower window member 104 configured to close an opening of the sample cell outer frame, a sample cell inner frame 106 having narrower openings at both ends than the openings of the sample cell outer frame, and an upper window member 105 configured to close an opening of the sample cell inner frame, in which at least one of the lower window member and the upper window member is made of a material that transmits X-rays, the sample cell inner frame is inserted into the sample cell outer frame, and a gap between the lower window member and the upper window member is filled with a fluid sample 100.