International combustion engine with balancer device

An internal combustion engine, comprising:

• three or more cylinders arranged in a row in a cylinder row direction;
• and
• a balancer device for reducing engine vibration,
• wherein the three or more cylinders include:
• a cylinder A arranged at an end in the cylinder row direction;
• a cylinder B arranged adjacent to the cylinder A;
• and a cylinder C provided with a piston that moves in a direction opposite to a piston of the cylinder A during a crank angle period in which the piston of the cylinder A and a piston of the cylinder B move in a same direction as each other,
• wherein the balancer device includes a balancer shaft arranged so as to extend from the cylinder A to the cylinder C along the cylinder row direction in a crank chamber, and
• wherein the balancer shaft includes:
• a first opening formed on an outer surface of the balancer shaft at a first location associated with the cylinder A in the cylinder row direction;
• a second opening formed on the outer surface of the balancer shaft at a second location associated with the cylinder C in the cylinder row direction;
• and
• a communication passage formed inside the balancer shaft so as to connect the first opening with the second opening.