Since the chewing gum method (Ozawa et al. 1959, Hada 1977) was thought to be suitable for measuring masticatory ability from infants to aged subjects in field studies, its methodology and characteristics were investigated.1. Concrete methodology for application of this method in field studies was established.2. It was ascertained that the masticatory ability of even 3-year-old infants could be measured with this method.3. Since the amount of sugar elution from chewing gum was related to the strength and rhythm of mastication, it was considered an indicator of the chewing ability of individuals.4. The amount of sugar elution showed a relation with the type of occlusion in 3-year-old infants, but not in adult subjects.