In this study, chitinase activity in an incubation broth of Aeromonas schubertii was measured using colloidal chitin azure as the substrate. More specifically, the induction of chitinases due to amendment with various carbon sources was examined. The highest chitinase activity was found following amendment with 0.5-1.0 % chitin powder, whereas the activity increased negligibly due to amendment with other carbon sources, such as glucose, GlcNAc, GlcN, sorbitol, sucrose, cellulose, or starch. The chitinase activity induced by the chitin powder was suppressed when the glucose, GlcNAc, GlcN, or starch was added simultaneously to the medium but was not suppressed by the addition of sorbitol, sucrose, or cellulose. The activity of chitinase in the crude extract was also not directly inhibited by glucose. Taken together, these findings suggest that the induction of chitinase activity depends on the acquisition of suitable carbon sources from the environment and that induction occurs at a regulatory level.