Internal combustion engine

An internal combustion engine comprising

• a crankcase that defines a crank chamber,
• a crankshaft that has a crank housed in the crank chamber and is rotatably supported on the crankcase,
• a cylinder block that is joined to the crankcase and defines a plurality of cylinders in a horizontally-opposed arrangement,
• a connecting rod that is linked to a piston housed individually in each of the cylinders via a small end and is linked to a crank pin of the crankshaft via a big end connected to the small end by a shaft part,
• a to-be-detected body that rotates integrally with the crankshaft, and
• a detection sensor that extends through the crankcase from an upper face of the crankcase, is made to face a trajectory of the to-be-detected body, and generates a pulse signal in response to movement of the to-be-detected body,
• the detection sensor being mounted on the crankcase between a vertical plane that includes a rotational axis of the crankshaft and is orthogonal to a cylinder axis of the cylinder and a cylinder that is at a rearmost position of the vehicle.