Cellobiose and glucose are valuable products that can be obtained from enzymatic hydrolysis of cellulose. This study discusses changes in the crystalline form of celluloses to enhance the production of sugars and examines the effect on structural properties during enzymatic hydrolysis. Various crystalline celluloses consisting of group I (cell I, cell IIII, cell IVI) and group II (cell II, cell IIIII, cell IVII) of similar DPs were prepared as starting materials. The similar DP values allowed a more direct comparison of the hydrolysis yields. The outcomes were analyzed and evaluated based on the residues and supernatants obtained from the treatment. As a result: (1) action of the cellulase of Trichoderma viride decreased both DP and crystallinity, with greater changes in group II celluloses, (2) the polymorphic interconversion process that occurred for cell IIII, cell IVI, cell IIIII and cell IVII during the treatment was independent of the enzymatic hydrolysis, thus, the hydrolysis behaviors depended on the starting material of the celluloses, and (3) higher sugar production was obtained from cell IIII and group II. Therefore, the hydrolysis behavior of the various crystalline celluloses depended on the particular polymorph of the starting material.