A medical image diagnosis apparatus according to an embodiment includes obtaining circuitry, detecting circuitry, deriving circuitry, and controlling circuitry. The obtaining circuitry is configured to obtain image data of a patient. The detecting circuitry is configured to detect each of a plurality of sites of the patient from the image data. The deriving circuitry is configured to derive information about a structuring member in the patient, on the basis of a detection result obtained by the detecting circuitry. The controlling circuitry is configured to determine an injection condition for a contrast agent to be administered to the patient for a contrast-enhanced scan, on the basis of the information about the structuring member.