Background: Acrylic resin is the most common material used in making the denture. Acrylic resins are available in powder and solution. The main component of the acrylic resin powder is polymethylmethacrylate while the main component of the acrylic resin solution is methylmethacrylate. Acrylic resin has several advantages, the price is relatively cheap, easily manipulated, stable in the oral cavity, and in terms of aesthetic have similar colour. The low thermal conductivity and mechanical strength, brittleness, high thermal expansion coefficient and low modulus of elasticity of the acrylic resin acrylic resin cause prone to fracture. Hence it is very necessary to develop of acrylic resin with a high modulus of elasticity in order to improve reliability. One material that can improve tensile strength and Young's modulus increase is an increase in the percentage of chitosan. Chitosan is the deacetylation of chitin which can be obtained from the skin of insects, shrimp, and crabs. Chitosan is recommended as a good functional material because it has good natural polymers such as biodegradable, biocompatible, and is not toxic. Objective: This study aimed to know the effect of nano chitosan concentration of the modulus of elasticity of acrylic resin. Methods: The research method is experimental laboratoris with a sample of 16 pieces measuring 64mm x 10 mm x 2.5 mm. Samples were assayed using UTM appliance. Data were analysed using One Way Anova. Results: A total of 16 samples were tested, obtained an average yield of acrylic resin as a control was 22.63, acrylic resins with nano chitosan concentration of 0.13% is 30.35, nano chitosan concentration of 0.26% is 28.16 and the concentration of 0.4% chitosan nano is 22,27. Test results analysis using One Way ANOVA value p of 0.231(p> 0.05) Conclusion: There is no effect of nano chitosan concentration given in acrylic resin that does not cause an increase in the modulus of elasticity.