Ultrasonic images (302) are created by means of an ultrasonic probe (104). Volume image data (221) is created previously by using an image diagnosis apparatus (102) and stored in a volume data storage unit (107). From the stored volume image data (221), a tomogram corresponding to the scan surface of the ultrasonic images is extracted, and a reference image (301) is formed from the tomogram. The ultrasonic image (302) and the reference image (301) are displayed on the same screen (114). The reference image (301) is being freezed in accordance with an input instruction. An instruction for adjustment when the frozen reference image (301) and the ultrasonic image (302) corresponding to movement of the ultrasonic probe (104) are displayed on the same cross section. Thereafter, the association relationship between the coordinate system of the ultrasonic image (302) and the coordinate system of the volume image data (221) is corrected in accordance with the instruction for adjustment based on a scan-plane coordinate of the ultrasonic probe (104) during the adjustment and a scan-plane coordinate of the ultrasonic probe (104) during the freezing.
