Amylose and Amylopectin is the material on starch which is the raw material of making Biodegradable plastic, but easy to tear (brittle), so need addition of plasticizer. In this study using Glycerol as plasticizer. This research was conducted at Polymer Chemical Laboratory of University of Sumatera Utara and Physics Laboratory of FMIPA and Universitas Syahkuala with the aim to make Biodegradable plastic and know physical characteristics of three types of tuber starch with addition of glycerol plasticizer. The experiment was compiled using a complete randomized factorial design with three replications. Factors are the types of starch (sago starch, arrowroot, and cassava). Observations include chemical and physical properties of starches and physical properties of biodegradable plastics. Data obtained for Amylose and Amylopectin content are the biggest Sagu starch (21.7% - 62.51%), starch (19.4% - 59.35%) and wood starch (18.0% 60,15%. The result showed that Amilosa and Amilopectin content highly influenced tensile strength and elongation of Biodegradable plastic. The higher the Amylose value, the value of tensile strength and elongation of Biodegradable plastic increasingly but for sago starch has elongation value and strength of tensile strength (97,83 kgf / mm2 - 4,83%) for starch (98,97 kgf / mm2 - 3,38%) and cassava starch (89.83 kgf / mm2 - 2.26%), this occurs because of the impurity and error factor in the thickness measurement of Biodegradable plastic.