To provide a continuous combustion type piston engine little in loss.

In a continuous combustion type piston engine wherein working medium flowing out of a combustion chamber is fed at least to two cylinders in order, the respective cylinders 20 are fixedly disposed in position with regard to the combustion chamber 1, and they are provided with inlets and an open/ close control means is provided, which connects the entrances with the combustion chamber 1 in order, or separates the entrances from the combustion chamber 1.