An image processing apparatus according to an embodiment includes processing circuitry. The processing circuitry performs a fluid analysis using image data including a blood vessel to calculate an index value relating to blood flow in the blood vessel. The processing circuitry specifies a plurality of target sites in the blood vessel in the image data. The processing circuitry changes analysis conditions for the fluid analysis corresponding to the positions of the target sites. The processing circuitry causes a display to display, in a comparative manner, the index value relating to blood flow calculated under the changed analysis conditions for the target sites.