Provided is a cell analysis method in a cell analysis device D that uses an optical path length image of a cell colony formed of a large number of cells to analyze the cell colony, the method comprising: acquiring the optical path length image of the cell colony by an acquisition unit of the cell analysis device; extracting a circular shape corresponding to a cell nucleus of the cell in the acquired optical path length image by an extraction unit of the cell analysis device extracts; comparing an inner optical path length of the extracted circular shape and an outer optical path length of the extracted circular shape by a comparison unit of the cell analysis device extracts; and analyzing the cell colony based on the comparison result by analysis unit of the cell analysis device.