Abstract: A study was conducted to evaluate the effects of non-starch polysaccharide (NSP) enzyme on digestive enzyme activity and apparent digestibility of Japanese flounder (Paralichthys olivaceus). The NSP-enzyme pretreated soybean meal (SBM) was obtained by fermentation with Candida utilis. Four isonitrogenous and isocaloric diets were formulated. The control diet contained 68.0% fish meal (FM) as the main protein source, whereas 45% of FM protein was replaced by SBM protein in the SBM diets with 0 and 0.2% NSP-enzyme. The NSP-enzyme pretreated SBM diet was formulated in which NSP-enzyme pretreated SBM protein replaced 45% of FM protein. At the end of the feeding trial, the digestive enzyme activities (P<0.01) and apparent digestibility (P<0.05) of fish fed the SBM diet without NSP-enzyme were significantly lower than those in control. Comparing with the SBM diet without NSP-enzyme, the fish fed the SBM diet supplemented NSP-enzyme showed significantly higher digestive enzyme activities (P<0.01) and apparent digestibility (P<0.05). The digestive enzyme activities and apparent digestibility of fish fed NSP-enzyme pretreated SBM diet were not significantly different from those of the SBM diet without NSP-enzyme (P>0.05).