An image processing device, comprising: a storage unit including an image processing storage unit storing a processing procedure for an image that is processed by the image processing device; a calculation unit including an image processing unit configured to acquire an observed image in which a cell is imaged by a microscope device, to perform image processing on the observed image on the basis of the form of the structures of the observed image and to output an image obtained through the image processing as a processed image, wherein the image processing unit is configured to perform expansion processing and contraction processing to the observed image by applying a processing mask (MSK, MSK1, MSK2) to the observed image which has a size determined on the basis of the state of the observed image; an image processing method selector configured to determine an observed image processing method for analyzing the observed image by comparing a statistical quantity (D1 or D2) of pixel values of the processed image (MP1 or MP2) with a predetermined reference value wherein the image processing method selector selects an image processing method for an early culture phase or an image processing method for a terminal culture phase as the observed image processing method by comparing the statistical quantity (D1 or D2) of pixel values of the processed image (MP1 or MP2) with the predetermined reference value; a cell image identification unit configured to extract an image of cells in the early culture phase or the terminal culture phase from the observed image on the basis of the observed image processing method selected by the image processing method selector and to output the extracted result as an identification result image and to output an identification result image indicating a result of identifying the image of the cell. a storage unit including an image processing storage unit storing a processing procedure for an image that is processed by the image processing device; a calculation unit including an image processing unit configured to acquire an observed image in which a cell is imaged by a microscope device, to perform image processing on the observed image on the basis of the form of the structures of the observed image and to output an image obtained through the image processing as a processed image, wherein the image processing unit is configured to perform expansion processing and contraction processing to the observed image by applying a processing mask (MSK, MSK1, MSK2) to the observed image which has a size determined on the basis of the state of the observed image; an image processing method selector configured to determine an observed image processing method for analyzing the observed image by comparing a statistical quantity (D1 or D2) of pixel values of the processed image (MP1 or MP2) with a predetermined reference value wherein the image processing method selector selects an image processing method for an early culture phase or an image processing method for a terminal culture phase as the observed image processing method by comparing the statistical quantity (D1 or D2) of pixel values of the processed image (MP1 or MP2) with the predetermined reference value; an image processing unit configured to acquire an observed image in which a cell is imaged by a microscope device, to perform image processing on the observed image on the basis of the form of the structures of the observed image and to output an image obtained through the image processing as a processed image, wherein the image processing unit is configured to perform expansion processing and contraction processing to the observed image by applying a processing mask (MSK, MSK1, MSK2) to the observed image which has a size determined on the basis of the state of the observed image; an image processing method selector configured to determine an observed image processing method for analyzing the observed image by comparing a statistical quantity (D1 or D2) of pixel values of the processed image (MP1 or MP2) with a predetermined reference value wherein the image processing method selector selects an image processing method for an early culture phase or an image processing method for a terminal culture phase as the observed image processing method by comparing the statistical quantity (D1 or D2) of pixel values of the processed image (MP1 or MP2) with the predetermined reference value; a cell image identification unit configured to extract an image of cells in the early culture phase or the terminal culture phase from the observed image on the basis of the observed image processing method selected by the image processing method selector and to output the extracted result as an identification result image and to output an identification result image indicating a result of identifying the image of the cell.