An X-ray diagnosis apparatus detects X-rays output from an X-ray source and transmitted through a subject, and generates images of the inside of the subject, and comprises a detector, an X-ray intensity distribution data generator, and an entrance dose distribution data generator. The detector detects the intensity of the X-rays output from the X-ray source. The X-ray intensity distribution data generator generates X-ray intensity distribution data showing the X-ray intensity for each of a plurality of subdomains of an X-ray irradiation field from the X-ray source based on the detection outcome by the detector. The entrance dose distribution data generator generates entrance dose distribution data showing the dose of X-rays output from the X-ray source and irradiated onto the subject, based on the X-ray intensity distribution data.