A medical image-processing apparatus according to an embodiment includes processing circuitry configured to determine a position of a feature point of a device in a first X-ray image, and generate a superimposed image in which a 3D model expressing the device is superimposed on the first X-ray image or a second X-ray image that is acquired later than the first X-ray image. The processing circuitry is configured to superimpose the 3D model on the first X-ray image or the second X-ray image at a position based on the position of the feature point.