An X-ray diagnostic system according to an embodiment includes: an X-ray tube for radiating an X-ray to the subject on the basis of a tube current for taking a scanogram of a subject; an X-ray detector for detecting the X-ray radiated by the X-ray tube and transmitted through the subject; a data collector for collecting X-ray dose distribution data, which shows the dose distribution of the X-ray; an image processor for creating the scanogram from the X-ray dose distribution data; a genuine data generator for generating genuine data showing the dose distribution of the X-ray, from the scanogram; a threshold value setting section for setting a threshold value for the genuine data; and a tube current adjustor for adjusting a tube current for taking a tomographic image of the subject in accordance with a comparison between the X-ray dose in the genuine data and the threshold value.