Piston machine, which is suitable for operating as an internal combustion engine, comprising at least one operating cylinder with at least one smooth internal surface area , and within said cylinder there is tightly matching inserted a piston , which is translatory oscillating movable to and fro in the axial direction (X) of said cylinder along said internal surface area thereof, wherein said piston is in an open first end portion of said cylinder furnished with a piston rod and is pivotally around a transversal diametrical axis (Y), which extends perpendicularly with respect to the previously mentioned longitudinal axis (X) of the cylinder , connected with its first end portion , wherein the second end portion of said piston rod is embedded on an eccentric crank shaft , and wherein the second end portion of the cylinder is closed, optionally by means of a cylinder head , and wherein each combustion chamber of the engine in each position of said piston during its movement along said axial direction (X) of the cylinder is defined with said internal surface area of the cylinder, the closed end portion of said cylinder as well as with a front surface of the piston , and wherein said cylinder is in the area of said combustion chamber furnished with at least one aperture , which is sealable by means of a valve and is adapted for transporting each media towards the interior of the cylinder , as well as at least one aperture which is sealable by means of a valve and is adapted for transporting each media from the interior of the cylinder towards the exterior thereof, whereas said engine is furthermore optionally furnished with a suitable control assembly , which is adapted for closing and opening said apertures by means of said valves with respect to each position of the piston within the cylinder , wherein the combustion chamber within the cylinder is in a direction away from said piston rod extended by a conical chamber having a pre-determined angle (α) of its tip , and wherein said piston is on its side, which is faced away from the piston rod , furnished with a truncated conical protrusion having a pre-determined angle (β) of its tip , wherein said angle (β) on said protrusion on the piston is determined in such way that said truncated conical protrusion on the piston is insertable into said conical chamber in the cylinder , characterized in that said smooth internal surface area of the cylinder is on its side, which is faced away from the piston rod , ended with a radially inwards protruding upper rectangular step , and on the opposite side, which is faced towards the piston rod , with a radially inwards protruding lower rectangular step , while the piston is on its side, which is faced away from the piston rod , furnished with a radially outwards protruding rim , the outer diameter of which is adjusted on the one hand to the internal diameter of said smooth internal surface area of the cylinder and on the other hand also to said steps , and in that said apertures , which are sealable by means of said valves and are suitable for transporting of media into or from said cylinder , are arranged in the area of said smooth cylindrical internal surface area between said steps . <EOS>