A medical image diagnosis apparatus according to an embodiment includes processing circuitry. The processing circuitry is configured to obtain operation information used for putting a surgery assistance robot into motion, the surgery assistance robot holding a medical tool to be inserted into the body of a subject and being configured to move the medical tool. The processing circuitry is configured to estimate the position of the medical tool with respect to a surrounding site expected after the medical tool is moved, on the basis of a positional relationship between the medical tool inside the body of the subject and the surrounding site as well as the operation information and is configured to control the motion of the surgery assistance robot on the basis of a result of the estimation.
