Introduction: B. rotunda used as a traditional medicine to treat illnesses such as rheumatism, muscle pain, febrifuge, gout, gastrointestinal disorders, flatulence, carminative, stomach ache, dyspepsia, and peptic ulcer. To enhance the stability, solubility and activity of the extract B. rotunda, should be developed into a product nanoparticles. Objective: This work reports the synthesis of nanoparticles produced by ethanol extract of Boesenbergia rotunda rhizome loaded with chitosan and alginic acid, and its biological activity test as antioxidant. Method: The synthesis of nanoparticles used an ionic gelation. Activity of the nanoparticle products as antioxidant was tested by the DPPH (2,2-diphenyl-1-picrylhydrazyl) method. Results: This work showed that nanoparticles chitosan produced by ethanol extract B. rotunda can be synthesized at a concentration (% w/v) of chitosan/ Na-TPP (sodium tripolyphosphate) and ratio of 8: 1, the size range of the nanoparticles were 389 to 877 nm, with a zeta potential of + 41.87 mV, and precentage nanoparticle 98.1%. The corresponding nanoparticles alginic acid can be synthesized at a concentration (% w/v) of alginic acid/ Ca2+ and ratio of 5: 1, the size range of the nanoparticles were 197 to 877 nm, with a zeta potential of -82.1 mV, and precentage nanoparticle 90.2%. Furthermore, nanoparticles result of the combination of alginic acid –chitosan can be synthesized at a concentration (% w/v) alginic acid/chitosan/ca2+ and ratio of 6.7: 2: 1, the size range of the nanoparticle were 226 to 877 nm, and precentage nanoparticle 29.7%. The morphology of each nanoparticle products was spherical and a smooth surface. The chitosan-alginic acid nanoparticles show higher activity than the starting material ethanol extract of B. rotunda.