the crankshaft 4 is kept small so that the center of gravity of the internal combustion engine and thus the center of gravity of a vehicle to which the engine is mounted is lowered however when an attempt is made to increase the piston stroke by using the multiple link type piston crank mechanism the total height of the internal combustion engine is increased by an amount corresponding to the increased piston stroke if an attempt is made to increase the piston stroke while maintaining the total height of the internal combustion engine at a certain value the position of the piston at the bottom dead center approaches the rotational center of the crankshaft as a result the outer peripheral portion of the crankshaft and the piston may interfere with each other japanese unexamined patent application publication no 63 88217 and is incorporated herein in its entirety focuses on the problem that the piston and the crankshaft interfere with each other however in the present exemplary embodiment the above described structure makes it possible to prevent the counterweight and the piston pin boss from interfering with each other at the timing that is close to the bottom dead center of the piston stroke of the internal combustion engine the distance from the lower end of the piston 1 to the main journal center 15 at the bottom dead center can be smaller than that in the internal combustion engine using a simple link type piston crank mechanism or in the related multiple link type combustion engine in other words using the crankshaft 4 according to the present disclosure while maintaining the height of the cylinder block of the internal combustion.