Abstract: Study on nanoparticle of herbs on the antimicrobial activity is lacking in the literature, thus this study was conducted with the aimed to evaluate the effectiveness of coarse (CP), fine (FP) and nanostructured ginger rhizome particles (NP) against growth of Escherichia coli, Pseudomonas aeruginosa, Salmonella typhimurium, Streptococcus pyogenes, Staphylococcus aureus, Bacillus subtilis, Rhizopus sp, Aspergillus nige, Candida albicans by using disc diffusion assay. NP had the strongest inhibitory effect against all tested bacteria (8.3 mm) followed by FP (7.5 mm) while CP (6.7 mm) showed the weakest maximum inhibition zone respectively (p < 0.05). However, ginger rhizome water extract at all particle sizes were found not to inhibit yeast and mold. Nanosize particle of ginger rhizome water extract able to inhibit bacteria better than the CP and FP. Hence it is suggested that nanosize particle ginger rhizome water extract has the potential to be used as antibacterial agent in food and pharmaceutical industry.