The surface of biomaterials with a fine micro/nano-pattern reportedly affects cell behavior. Chitosan was previously shown to exhibit antibacterial properties and thus here we evaluated the cellular response and antibacterial activity of chitosan micro/nano patterns prepared by the imprint method. We fabricated micro/nano patterns with different sizes and shapes of pillars, grooves, and holes. The chitosan pattern films exhibited antibacterial activity towards Streptococcus mutans. In addition, we observed mammalian cells adhering to and spreading on the chitosan pattern, and found that the orientation of the cells was controlled by the shape of the pattern.