The swimming motion of Tuna type fishes has excellent ability for its speed and efficiency. And some studies have been reported about the most efficient swimming motion by using numerical analysis on two dimensional oscillated wing theory. And several fish type robots are developed based on these studies, but almost all robots have spring held tail fin. Because the tail of tuna type fishes is very smart, and very difficult to implement the tail fin angle actuate mechanism. So, these fish type robots cannot confirm theoretical result by experimental way. So we designed and developed smart tail fin angle actuating mechanism which can swim maximum 2.0m/s as reported in previous reports7) 8) 9) 10). And made some experiments about the relationship between the swimming motion scheme and the swimming speed. So, this paper studies about the difference of the propulsive force between tuna type tail fin and rectangular type tail fin by experimental and numerical way.