A mobile tour-guide robot is a very attractive tour-guide in the exhibition hall of science museums and the necessity of tour-guide robots for museums is gradually increasing. Two kinds of robots have served as tour-guide robots in an exhibition hall of the Korea National Science Museum which is a very densely populated museum of many people and exhibits. The robots move around the large exhibition area and provide guide services to lots of visitors. A robot leads the way to the exhibit that a visitor wants to find and it takes the shortest route. Robots were operated for four months from January to April 2011, and we observed behavior of visitors and collected subjective evaluation of users. The result shows that there are four stages of using a mobile tour-guide robot and some differences of subjective evaluations depending on the gender and the age of the user and we suggest several improvements on the mobile tour-guide robot.