1. An incubated state evaluating device, comprising: an image reading unit reading a plurality of images in which a plurality of cells incubated in an incubation container are image-captured in time series; a feature value calculating unit obtaining, for each of the cells included in the images, each of feature values representing morphological features of the cells from the images; a frequency distribution calculating unit obtaining each of frequency distributions of the feature values corresponding to the respective images; and an evaluation information generating unit generating evaluation information evaluating an incubated state of the cells in the incubation container based on a variation of the frequency distributions between the images.