In displaying a tomographic image in a slice in a three-dimensional (3D) medical image, for the purpose of achieving better recognition of a vascular structure contained in the slice without degrading spatial resolution of the slice, there is provided an image processing apparatus comprising: identifying section for identifying a slice of interest in a 3D medical image representing an anatomical part including a blood vessel and projecting section for applying projection processing to pixel values in a slice axis direction of the slice for a region in the 3D medical image including the slice and wider than a slice width of the slice.
