A variable compression ratio internal combustion engine comprising: a variable compression ratio mechanism arranged to vary an engine compression ratio in accordance with a rotation position of a first control shaft; an actuator arranged to vary and hold the rotation position of the first control shaft; and a link mechanism arranged to connect the actuator and the first control shaft, the link mechanism including; a second control shaft disposed in parallel with the first control shaft, a lever connecting the first control shaft and the second control shaft, a combustion load acted to the first control shaft being transmitted through the lever to the second control shaft, a first arm portion extending from the first control shaft in a radially outward direction, a first link pin which is inserted through a tip end of the first arm portion and one end of the lever, and which connects the first arm portion and the lever so that the first arm portion and the lever are rotated relative to each other, a second arm portion extending from the second control shaft in the radially outward direction, and a second link pin which is inserted through a tip end of the second arm portion and the other end of the lever, and which connects the second arm portion and the lever so that the second arm portion and the lever are rotated relative to each other, characterized by the first link pin having a diameter larger than a diameter of the second link pin. a variable compression ratio mechanism arranged to vary an engine compression ratio in accordance with a rotation position of a first control shaft; an actuator arranged to vary and hold the rotation position of the first control shaft; and a link mechanism arranged to connect the actuator and the first control shaft, the link mechanism including; a second control shaft disposed in parallel with the first control shaft, a lever connecting the first control shaft and the second control shaft, a combustion load acted to the first control shaft being transmitted through the lever to the second control shaft, a first arm portion extending from the first control shaft in a radially outward direction, a first link pin which is inserted through a tip end of the first arm portion and one end of the lever, and which connects the first arm portion and the lever so that the first arm portion and the lever are rotated relative to each other, a second arm portion extending from the second control shaft in the radially outward direction, and a second link pin which is inserted through a tip end of the second arm portion and the other end of the lever, and which connects the second arm portion and the lever so that the second arm portion and the lever are rotated relative to each other, a second control shaft disposed in parallel with the first control shaft, a lever connecting the first control shaft and the second control shaft, a combustion load acted to the first control shaft being transmitted through the lever to the second control shaft, a first arm portion extending from the first control shaft in a radially outward direction, a first link pin which is inserted through a tip end of the first arm portion and one end of the lever, and which connects the first arm portion and the lever so that the first arm portion and the lever are rotated relative to each other, a second arm portion extending from the second control shaft in the radially outward direction, and a second link pin which is inserted through a tip end of the second arm portion and the other end of the lever, and which connects the second arm portion and the lever so that the second arm portion and the lever are rotated relative to each other, characterized by the first link pin having a diameter larger than a diameter of the second link pin.