The greater omentum of the cats is said to have a lace-like structure. However, there are only a few descriptions on whether pores exist, and there are not many morphological studies on this meshwork. In this study, the greater omentum of the cats was observed at each age of development using a scanning electron microscope. The greater omentum of the cats immediately after birth was found to be continuous, and no pores were observed. Also, development of microvilli was observed in the mesothelial cells on the surface of the greater omentum. In young cats at 3 months of age, small pores were sporadically observed, and at the ages of 6–12 months, there were more and larger pores. It was estimated that the pores on the greater omentum are formed in the process of moving from the movement of organs, such as the stomach, intestines and diaphragm, and the presence of these pores enables the passage of ascites between the omental bursa, the greater omentum and the serosal cavity of the wall without flowing through the omental foramen.