1. A medical image processing device, comprising: an image dividing unit which divides an image corresponding to a subject image which is picked up by a medical image pickup apparatus into a plurality of regions constituted of at least one or more pixels; a feature value calculating unit which calculates a color tone feature value which is a feature value based on a color tone of the image in each of the plurality of regions; a first color tone reference value calculating unit which calculates a first color tone reference value based on the color tone feature value which each of the plurality of regions has; a first lesion detection reference calculating unit which properly calculates a first lesion detection reference for detecting a lesion finding in accordance with the first color tone reference value; and a first image region detecting unit which detects a first target region that is a region in which an image of the lesion finding is picked up among the respective plurality of regions, based on the first lesion detection reference and the color tone feature value which each of the plurality of regions has.