Utilizing the mathematical method for experimental analysis on occlusal curves, which is based on three-dimensional analytical geometry. and using the data measured by Nodauna et al of three-dimensional positions on maxillary dental casts of twenty-two male and female young Japanese having clear cusps, Experimental analysis of curve of Spee, curve of Wilson, and sphere of Monson have been performed. As the result, the most probable position of the center of the curve of Spee existed in between 110-130mm superior to the incisal point and in between 0.6-4.4mm posterior to the incisal point. and further the most probable radius of the curve of Spee existed in 108.6-129.0mm within 0.27% of accuracy. Each radius of the curves of Wilson corresponding to each buccal and lingual cusps of Ist molar, and each buccal and lingual cusps of 2nd molar are separately determined definitely, and calculated. They are, 482.6mm, 363.4mm. 397.0mm, 297.8mm, respectively. The most probable position of the center of the sphere of Monson existed in between 110-130 mm superior to the incisal point, in between 8.5-4.7mm posterior to the incisal point, and the most probable radius of Monson existed in between 109.7-129.3mm within 0.22mm of accuracy.