Abstract: An ultrasound diagnosis apparatus generates first data, based on a result of transmission and reception that are executed when a probe is located at a first position of a subject. The apparatus generates second data, based on a result of transmission and reception that are executed when the probe is located at a second position. Under a first constraint on an orientation of a section, the apparatus extracts, from the first data, first sectional image containing a structural object inside the subject and taken along a direction in which the object extends. Under a second constraint on the orientation of a section, the apparatus extracts, from the second data, second sectional image containing the object and taken along a direction in which the object extends. The apparatus generates joined image data composed of at east a part of the first sectional image and the second sectional image joined together.