An image processing apparatus includes display control means for displaying, on display means, a blend image obtained by performing blend processing at a variable transmissivity in accordance with an instruction of an operator using an optical coherence tomography (OCT) image and an OCT angiography (OCTA) image of mutually corresponding regions in a subject that are acquired by an OCT, setting means for setting a region of interest in the displayed blend image, and execution means for executing processing on the set region of interest in at least one image of the OCT image and the OCTA image.