According to one embodiment, an apparatus includes a slice image generation unit, a three-dimensional image generation unit, a display unit, a setting unit, an updating unit, and a changing unit. The slice image generation unit generates the data of slice images based on a volume data. The three-dimensional image generation unit generates the data of a three-dimensional image based on the volume data. The display unit displays the slice images and the three-dimensional image. The setting unit sets the vector on the first slice image of the displayed slice images in accordance with an instruction from an operator. The updating unit updates the displayed three-dimensional image based on the vector. The changing unit changes the position of a slice of a remaining slice image of the displayed slice images to a position where the slice intersects the vector and is perpendicular to the slice of the first slice image.