To provide a fluorescent beam analyzing device and a fluorescent beam analyzing method capable of sufficiently exciting a sample to emit the fluorescent beam from the sample even if a width of the exciting x-ray for radiating the sample is narrow.

As an image forming device 1, a plate 1P provided with a pin hole 1A corresponding to an optical axis 7 is arranged over the sample S. An imaging plate 2A as a fluorescent X-rays detector 2 is arranged over the plate 1P freely to be rotated, and a sample holder 3 to be loaded with the sample S is formed freely to be rotated. The sample S is rotated in-plane around the optical axis 7, and the fluorescent X-ray detector 2 is synchronously rotated with the rotation of the sample around the optical axis 7, and while the exciting X-ray L0 having a narrow width is radiated to the sample S to excite the sample. The exciting X-ray L0 excites the whole surface of the sample, and a fluorescent X-ray image corresponding to the whole range of the radiation can be formed in the fluorescent X-ray detector 2.