1. A culture quality evaluation method, comprising: a first step of culturing a pluripotent stem cell under a predetermined culture condition and thereby creating a sample; a second step of imaging a proliferated cell colony in the sample and accordingly capturing an original image; a third step of dividing the original image into smaller images of a predetermined size and calculating standard deviations of pixel values of pixels contained in each one of the smaller images; and a fourth step of judging that the sample is an acceptable sample when a ratio of a number of the smaller images whose values of the standard deviations are within a predetermined range to a total number of the smaller images is equal to or smaller than a predetermined threshold value and judging that the sample is an unacceptable sample when the ratio is beyond the threshold value.