PROBLEM TO BE SOLVED: To provide a body position determination support device and a medical image diagnostic apparatus that enable anyone to cause a patient to take an appropriate body position during a treatment by determining a state unique to the patient before the treatment, and to check a change in the body position during the treatment, and notify as needed.SOLUTION: A body position determination support device includes: an imaging device C for imaging a posture of a patient an attention region setting part 1f for setting information on a region and an area of the patient to which attention needs to be paid a body position determination support part 10 for analyzing a moving image of the patient photographed by the imaging device C, acquiring a position on the image corresponding to the region and the area of the patient to which attention needs to be paid in conjunction with the movement of the patient, and adding a mark to the region and the area of the patient to which attention needs to be paid and a display part 1g for displaying the movement of the patient as an image together with the mark.
