An ultrasound diagnosis apparatus includes processing circuitry. The processing circuitry obtains three-dimensional medical image data, taken by using an ultrasound probe, of a region including a heart valve of a patient and a catheter inserted into a heart chamber of the patient. The processing circuitry determines an advancing direction of a tip end part of the catheter by obtaining information on a position and a posture of the tip end part included in the three-dimensional medical image data, by using at least one selected from shape information indicating the shape of the tip end part and reflection characteristic information indicating ultrasound reflection characteristics of the tip end part. The processing circuitry generates a display image from the three-dimensional medical image data in accordance with the position and the advancing direction of the tip end part. The processing circuitry causes the display image to be displayed.