We investigated the current situation of chimpanzee tourism at the Mahale Mountains National Park by direct observations of tourists, tour guides, and trackers. The median number of people in a tourist group was seven, which is within the number allowed by park regulations; however, the actual number was sometimes as large as 11 because groups occasionally included several trackers and guides in addition to six tourists. On 23.1% of 121 observation days, the number of groups observing chimpanzees was greater than that permitted by park regulations. This resulted in as many as 39 people visiting one group of chimpanzees in a day. Problematic behaviors on the part of tourists included moving too close to chimpanzees, observing chimpanzees without authorized park guides, and simultaneous observation by two or more groups of tourists, among others. Based on these analyses, we argue that better control of tourist groups is needed in order to reduce the potential negative impacts of tourism on chimpanzee health and behavior.