In this study, a sundial simulator was developed as a new teaching tool. Our simulator is easily used with Microsoft Excel, based on the contents learned until high-school natural science in Japan, and the geometrical calculation on the celestial sphere. Comparing the actual sundial measurements with the calculation of our simulator, the calculation accuracy of our simulator was about 6 minutes in time. Our simulator also has ease of use and can be made at low cost, so it may be expected to be used in school education.
