In this paper, in order to examine the possibility of the practical application of multiple cylinder type Stirling engine, the engine as hundred watts is designed, and friction loss, gas leakage and effect of the buffer pressure of the piston ring are examined. As the result, it is difficult that uses the piston ring for the engine of about 10W. In addition, it is the very ideal combination to adopt the injector as a piston and cylinder, if the durability is not considered.