An MRI apparatus 1 comprising an image producing unit 101 for producing a plurality of axial images D1 to D10 in a plurality of slices defined in a body part to be imaged containing a blood vessel； a classifying unit 102 for classifying the plurality of axial images D1 to D10 into a plurality of classes I to IV based on which a portion of the imaged body part each of the plurality of axial images D1 to D10 represents； and a defining unit 103 for defining a search region for searching for a blood vessel from within an axial image based on within which of the plurality of classes I to IV the axial image falls.
