Silver was traditionally known as substance that had antibacterial activity. In our previous work, we developed a small-sized nanoparticle generation device, which consisted of a cylindrical chamber including a plat plat type small ceramic heater and investigated for the particle generation characteristics of silver nanoparticles. In this study, we applied this generator to an antibacterial device. Antimicrobial activity of silver nanoparticles generated from our device was investigated using S. epidermidis gram-positive bacterium. The result showed that the number of colonies was near zero for the filter. In ten-minute exposure of silver nanoparticles, most of S. epidermidis bacteria did not grow on the filter surface.