We used L.P.G. and Gasoline for Rotary engine fuel, and experimented the Rotary engine performance opening full throttle. And then we compared with the performances using L.P.G. and Gasoline. Further, we made the similar experiment keeping constant the boost pressure. As the result, it has been made clear that was followed. * In full throttle opening, though the torque using L.P.G. is a little smaller than that using Gasoline at the low Engine speed, the difference between the two is distinguished as the speed is faster and it is about 10% in average. * In the test of performance fixed boost pressure the torque using L.P.G. is better than that using Gasoline too. * Specific fuel consumption using L.P.G. is better than that using Gasoline. But, during part-throttle conditions, the consumption of L.P.G. is worse than that of Gasoline, though it seems that the consumption of L.P.G. is better than that of Gasoline at the maximum economy mixtures.