An apparatus for culturing animal cells, includes a diagnosis system to make it possible to diagnose by measuring sizes of the cells by means of image processing while a system of culturing the animal cells is cut off from the outside of the apparatus system, a control system to control the culture conditions of a culturing cistern on the basis of a result of the diagnosis, and a culture medium regenerating system to remove waste contents in a culture medium. In the apparatus of this invention, the culture system and diagnosis system are cut off from the outside of the apparatus system. Therefore, no infection of miscellaneous microorganism, etc., occurs, nor does consumption of valuable cells and products occur. Further, since it is possible to easily obtain data of the proportions of division potential-possessing cells and living cells, the environmental factors to the culturing cistern can be easily and instantly controlled based on the data, and therefore, the culturing efficiency can be enhanced.