The holographic information capacity of film is analysed in terms of 3-dimensionsl reconstructed image. Information capacity I is defined by two factors M and K, being I=M log K in simple case, where M is the number of image elements and K the number of gray levels. In the case of holography the image elements are 3-diinensional. The number M of 3-d. image elements is deduced from diffraction, and it merely depends upon the film size. But the number K of gray levels depends upon the fluctuation of grain density in the film. The value of K is deduced with a model of "simplified film", using twice the "random walk" method. Then I is given as a function of a (the radius of film) and r (radius of grains in the film). The ourve of J vs a and of I vs r are given. It is discussed about how to chose the size and density of the grains under certain conditions.