Bioplastics made using the basic ingredients of canna tuber starch with sorbitol plasticizer and the addition of CMC variations have been carried out. This study aims to understand the effect of adding CMC to the mechanical properties and biodegradability of bioplastics in soil media. This research was carried out with 4 stages of work namely, extraction of starch from canna tubers, synthesis of bioplastic manufacturing using the blending method, testing mechanical properties in the form of thickness, tensile strength, elongation, and young modulus. Characteristics of functional groups have been tested using FTIR and bioplastic biodegradability testing has been carried out on soil media for 21 days by looking at weight loss from bioplastics. The variation of adding CMC used is 0; 0.25; 0.5; 0.75; 1; 1.25; 1.5 and 2 grams. The best mechanical properties are produced with thickness of 0.0795 mm, tensile strength of 27.53 MPa, elongation of 3.018% and young modulus of 885.66 MPa. The results of bioplastic biodegradation testing on soil media for 21 days showed that bioplastics made were biodegradable. Reduction of bioplastic mass in soil media by 86,032%.