Abstract: The invention relates to engine building. The inventive opposed internal combustion engine comprises two cylinders (1, 2) fitted with pistons (10, 11) therein, a triple crank shaft (7) connected to the first piston (10) of the first connecting rod (19) with the aid of a pivot and connected to the second piston (11) with the aid of the second and third connecting rods (20, 21); the first and second crossheads (12, 13) are mounted on corresponding guides (3,4) in such a way that they form cavities (26) inside which the second and third connecting rods (20, 21) are connected to the pin (5) of the second crosshead (13). The invention decreases the inertial forces of an alternately moving mass and the gas pressure exerted on the pistons, subject to observance of the engine balance.