1. An image processing device for detecting a human face from a subject image, the device comprising: an imaging unit that captures a subject image; and a detection unit that detects a face from the subject image and that has at least processing for detecting a relatively-large-size face as the face and processing for detecting a relatively-small-size face as the face, wherein the detection unit first repeats, a plurality of times, processing for detecting the relatively-large-size face and outputting a detection result, and subsequently performs processing for detecting the relatively-small-size face and outputting a detection result.