The present invention provides a cell culture vessel/sample observation cell that is capable of culturing cells or cell tissue in three dimensions and allowing a three-dimensional structure of the cells or the cell tissue to be perceived easily. The cell culture vessel/sample observation cell according to the present invention for containing a culture gel in which the cells or the cell tissue is embedded, comprises a frame, at least one window bordered by the frame, and at least one projection projecting from the frame inwardly into the cell culture vessel/sample observation cell, wherein the at least one window is light-permeable and nutrient component-permeable and is placed in such a way as to allow for multifaceted observation of the cells or the cell tissue, and the projection has a feature point to be placed at a position where the cells or the cell tissue as well as the feature point can be observed from the window.