having the flat portion along the edge as shown in fig1 so that the cell culture improving effect of the projections 101 is enhanced moreover by substantially eliminating the region of flat portion where the cells 108 are liable to adhere to the culture section 102 and in some cases by incorporating a structure which can prevent the cells 108 from being adsorbed to the culture section 102 and should they be adsorbed can prevent the adsorbed cells from being positioned on the culture section 102 there can be obtained an additional effect to prevent mixing of the cells cultured at the area having no projections when the projections 101 give a specific influence to the cells 108 in the present invention the u201c cell 108 u201d is a concept including the organized cultured cells represented by cultured tissue and organ cells in use of the cell culture vessel 100 according to the present invention culture is carried out with the culture solution 107 and cells 108 being placed on the culture section 102 in a thermostatic culture tank in the conventional way and there are conducted as required such operations as changing of the culture solution 107 taking out of the cells 108 supply of the reagents shaking observation by a microscope and in some cases freezing in a freezer during these unit operations the culture vessel must be transferred from one operating unit to another.