An X-ray diagnosis apparatus includes an X-ray irradiator, a light source device, and a light emission control unit. The X-ray irradiator emits X-rays to a subject. The light source device includes a light-emitting part and a light irradiation part. The light-emitting part includes a semiconductor laser or a light-emitting diode for emitting light. The light irradiation part emits the light as output light indicating the irradiation field of the X-rays. The light emission control unit controls the light-emitting part according to the operating state of the X-ray irradiator.