Background : Bamboo fiber contains 97% of dietary insoluble fiber from mature bamboo shoots. Bamboo contains phytosterols and a high amount of fiber which can be labelled as nutraceuticals or natural medicines that are attracting attention from the aspect of health. This study was conducted for the production of dietary fiber from Sinoarundinaria nigra, S (S. nigra) shoots barks by using α-amylase, alcalase, glucoamylase or Viscozyme and improvement of Large intestinal function in rats. Methods and Results : Yields of enzymatic degradation were 80.5% (322 g/400g) and the dietary fiver content of the enzyme digest was 69.7%. Sprague-Dawley rats were fed on diet containing 100 ㎎/㎏ and 200 ㎎/㎏ S. nigra dietary fibers [dietary fiver of bamboo shoots barks (SNDFB)] for one weeks. As a result of weighing of the fecal pellets, loperamide alone group showed a significant decrease compared with the control group, and it was significantly increased in test group (200 ㎎/㎏-SNDFB) compared to loperamide alone group. In addition, the measurement of gastrointestinal charcoal transit ratio in rats, loperamide alone group showed a significant decrease compared with the control group, and it was significantly increased in all the test substance groups compared to loperamide alone group. The number of remnant fecal pellets in the colon after dissection was significantly increased in the loperamide alone group compared to the control group, and was significantly decreased in the test substance groups compared to loperamide alone group. Conclusion : These results suggest that dietary fiber isolated from S. nigra has a marked effect on the improvement of bowel function in rats with loperamide (4 ㎎/㎏)-induced constipation.