We have been conducting an experiment with mixed reality technology in a museum in order to enhance visitors' experience in looking at the exhibits. The following example is an experiment at the dinosaur gallery at the National Science Museum in Tokyo, Japan. A handheld PC with a camera allows users to reconstruct the flesh of the dinosaur on display in the gallery. The superimposed images are interactive 3D computer graphics with mixed reality technology. Additional information, such as the names of the bones, can be displayed on the screen, and an audio guide can be played from the handheld PC. Users can change the skin texture and the skin color of the dinosaurs right in front of the skeletons in the museum gallery. Thinking about and choosing the skin images will enable children to think more scientifically about dinosaurs. We are currently developing a computer program that enables users to draw their own dinosaurs and save them on the Web. Users can then view their creations with mixed reality technology. We have also developed a user-friendly authoring tool to develop the program using mixed reality technology.