An X-ray CT apparatus has a plurality of projectors, a reception unit, a setting unit, a supporter, and a scan execution unit. The projectors each have a light source on a circumference having a same radius as a rotation radius of an X-ray focal point of an X-ray irradiator and each irradiate laser light having an irradiation range simulating an irradiation range of the X-ray. The reception unit receives an instruction for three-dimensionally sliding the projectors as one body. The setting unit sets a position of the projectors. The supporter supports a table and three-dimensionally slides the table by a difference between a position of a center of the circumference of the set projectors and a position of a rotation center of the X-ray focal point of the X-ray irradiator. The scan execution unit executes a scan with the table after the sliding as a scan position.
