Anomalies of the number of teeth include anodontia. The congenital absence of all teeth is called complete anodontia, and that of several teeth is called partial anodontia. Agenesis of numerous teeth causes a decrease in mastication and esthetic problems, and its treatment is often difficult.In the present paper, we report the case of a partial anodontia patient congenitally missing 6 primary teeth and some permanent teeth. The patient was treated using a denture for deciduous teeth to improve his masticatory function and esthetic appearance. The patient was a one–year and five–month–old boy who visited our hospital with a chief complaint of the delayed eruption of primary teeth. There was no significant past medical history. An X–ray image showed the congenital absence of the bilateral upper primary lateral incisors, bilateral lower primary central, and lateral incisors. A lower denture for deciduous teeth was placed when the patient became 3 years and 11 months as he was old enough to have his impression taken. Similarly, an upper denture for deciduous teeth was placed at the age of 4 years and 3 months when the bilateral primary upper second molars, used as abutments, had completely erupted. Despite his young age, the patient became used to wearing dentures, and improvement of his masticatory function and esthetic appearance during the primary dentition period were achieved. A long–term comprehensive maintenance program is planned with careful attention to the jawbone, dentition, and occlusal development in order to achieve functional permanent dentition.