In June 2015, Diagnostic Reference Levels was drawn up in Japan. Therefore, the exposure control of the examinees is more important than ever. In this research, in order to grasp the AGD for each examinee, a basic examination of a method to measure X - ray output without changing the quality of the beam was made. In order not to change the quality of the radiation, scattered radiation from the added filter is used and the added filter is mounted in the X-ray source device, so it is necessary to dispose the dosimeter also in the X-ray source device. It was measured with a semiconductor dosimeter. The measurement conditions, that are likely optimal judging from the examination results, are as follows: (1) The semiconductor dosimeter is to be cooled constantly due to its temperature characteristics. (2) The straight line connecting the added filter center and the semiconductor dosimeter?s detector center is to be orthogonal to the detection plane of the dosimeter?s detector constantly. (3) The dosimeter?s detector is to be opposed, at an angle not blocking the primary X-ray, to the added filter as much as possible. It is likely possible to calculate the X-ray output in mammographic X-ray apparatuses by multiplying the dose of the scattered radiation measured in the layout above by the respective calibration constant of each target/added filter combination. In addition, we believe that it is possible to grasp AGD by examinee by multiplying the X-ray output by coefficients additionally.