The inhibitory effect on the increasing the postprandial blood glucose levels by Banaba extract capsule enriched corosolic acid was evaluated. First of all, blood glucose levels of 12 subjects including of 7 males and 5 females were measured at the time of fasting and in 30, 60, and 120 minutes after being ingested only starch meal (540 kcal).   Then a soft capsule of Banaba extract contained high 10mg quantity of corosolic acid was orally administered to all subjects at every morning for two weeks.   The inhibitory effect by the capsule was evaluated to compare with the postprandial blood glucose levels by being ingested the only starch meal. As a result, a significant inhibitory effect was observed at the each point of fasting and 30, 60 and 120 minutes within only one week after administrating the soft capsule. Both the weight loss and the improvement of BMI were observed also after two weeks administrating. It is clear that the soft capsule of Banaba extract contained high 10mg quantity of corosolic acid is available, as no adverse effect was observed during and after the trial.