Five types of bite plates of lower full denture, with labial anterior region, lingual anterior region, buccal molar region, or lingual molar region cut off, and ordinary type, were prepared with ten edentulous patients as the subjects and the occlusal force of each bite plate was measured by strain gauge method. The actual basal surface area of the lower full dentures was measured by sticking aluminum foil on the lower jaw casts. The projected basal surface area of the lower full dentures was measured by photographs of the lower jaw casts taken from a point vertical to the occlusal plane. Occlusal forces and two kinds of measurement of surface area were compared and the bearing ability for occlusal force of five regions of the basal surface area was calculated per given area. The bearing ability of five regions of the basal surface area on occlusal force was then examined. The results were as follows : 1. In comparison of the occlusal force of the subjects, male subjects showed 21.9±4.64kg and female subjects 9.1±5.57kg, which were higher than the value generally reported. 2. Male subjects have comparatively greater occlusal force, about 2.4 times greater than female subjects. 3. The actual basal surface area of lower full denture was the largest at the lingual molar region (8.3cm^2), followed by the buccal molar region, labial anterior region, and lingual anterior region, in descending order. 4. The projected basal surface area was the largest at the buccal molar region (5.5cm^2), followed by lingual molar region, labial anterior region, and lingual anterior region, in descending order. 5. Bearing ability for occlusal force per given area of the actual basal surface area was the largest at the buccal molar region (0.25kg/cm^2), followed by lingual molar region, lingual anterior region, and labial anterior region, in descending order. 6. Bearing ability for occlusal force per given area of the projected basal surface area was the largest at the buccal molar region (0.18kg/cm^2), followed by lingual molar region, lingual anterior region, and labial anterior region, in descending order. From these results, the buccal molar region of the basal surface area of lower full denture plays a very important role in bearing occlusal force. In preparing lower full dentures, therefore, it is considered important to make this area as large as possible. Occlusal force in full dentures was found to be more closely related with projected basal surface area than with actual basal surface area. Therefore, enlarging horizontal area rather than enlarging vertical area was considered important in order to increase occlusal force in dentures. It was thought that extension of the border of the lingual molar region inferiorly would improve stability but not increase occlusal force.