PURPOSE: To correct an error due to a position shift of a sample easily at low cost by installing the 2nd radiation detector in addition to the 1st radiation detector which measures a sticking quantity by making fluorescent X rays from the sample irradiated with radiation incident.

CONSTITUTION: A radiation source 3 and the 1st and the 2nd radiation detectors 4 and 5 are fitted to the base 2 of the sticking quantity meter; and an irradiation field limiting mask 8 is fitted on the front surface of the radiation source 3 and a slit 6 and a mask 7 are fitted on the front surface of the detector 5. Then, the sample is run at a constant speed perpendicular to the paper surface at a position of distance l0 from the base 2. Then, components of fluorescent X rays arriving from the radiation source 3 the sample 1, i.e. components nearly perpendicular to the surface of the sample 1 are made incident on the detector 4, and the detector 5 is so installed that fluorescent X rays from the sample 1 or exciting X rays are at an angle θ much smaller than an angle of incidence on the detector 4, thereby an error in measurement due to a position shift of the sample 1 on the surface is corrected with the output of the detector.