An image processing method according to the invention comprises: obtaining three-dimensional image data representing a three-dimensional image of a fertilized egg in a cleavage stage obtained by imaging the fertilized egg by optical coherence tomography; extracting a blastomere region corresponding to an individual blastomere in the three-dimensional image for each blastomere based on the three-dimensional image data; counting a number of the blastomere region extracted in the three-dimensional image; obtaining a volume of each blastomere region based on the three-dimensional image data; and determining a number X of the extracted blastomere regions is expressed by a following inequality: 2N