This experiment was conducted to determine the effect of cutting length of rice straw on ruminating behaviour of sheep. Three ruminally fistulated sheep averaging 40 ㎏ body weight were assigned to a 3 × 3 Latin square design by cutting length of rice straw (3㎝, 9㎝ and 15㎝). The results are as follows: 1. Increasing cutting length of rice straw resulted in the increase of ruminating and total chewing time. 2. Number of chews during eating, ruminating and total chewing were increased as the cutting length of rice straw were longer. 3. The chewing speed 1 [Daily chewing numbers of ruminating/Daily ruminating Time(sec)] was in accordance with the cutting length, but chewing speed 2 [Daily total chewing numbers/Daily total chewing time(sec)] was more rapid when sheep were led 3㎝ cutting length of rice straw. 4. Eating rate of DM and NDF were increased as the cutting length of rice straw was shorter, but ruminating and chewing efficiency were the highest at 9㎝ cutting length. 5. Increasing in cutting length of rice straw resulted in increased number of boluses per day, but number of chews per bolus was in accordance with the cutting length of rice straw.