The cross sections of both amplitude and phase holograms are observed by electron microscopy. Holograms were recorded on Kodak 649F and Scientia 14C75 sheet films by using a He&sngbnd;Ne laser beam (6328 Å). It is shown that the holograms are recorded throughout the whole thickness of the emulsion layer and the developed grains are enlarged by bleaching (about 1.5 times by length). This enlargement can be correlated with the thickness change of the emulsion layer during the chemical processing in making holograms.