1. An image processing apparatus, comprising: an outline extracting processing unit inputting a phase contrast image of a cell colony acquired by an observing unit, and extracting an outline of the cell colony; an extracting unit extracting a feature quantity of an outline part of the cell colony based on brightness information at an outside and brightness information at an inside of the outline on the phase contrast image; and an automatic discriminating unit automatically discriminating whether or not the cell colony is an iPS cell colony based on a discriminant criterion determined in advance and the feature quantity extracted by the extracting unit.