An MRI apparatus comprises a image producing unit 101 for producing an image of a first body part containing a blood vessel； a defining unit 108 for defining a slice intersecting the image based on a reference position Q within the first body part, the slice being defined so that an angle of the slice is changeable with respect to the blood vessel VE； a unit for obtaining an index VI for deciding whether or not the blood vessel VE is contained within the slice for each angle θ； and a determining unit 111 for determining an angle of the slice at which the blood vessel VE is contained in the slice based on the index VI.
