Variable compression ratio internal combustion engine

A variable compression ratio internal combustion engine including a control shaft rotatably supported by an engine body, a variable compression ratio mechanism for changing an engine compression ratio in accordance with a rotational position of the control shaft, an actuator that rotatively drives the control shaft, and a speed reducing mechanism for reducing a rotational power of the actuator and for transmitting the speed-reduced power to the control shaft, the speed reducing mechanism having a rotation shaft rotatably supported in a housing fixed to the engine body and a lever that connects the rotation shaft and the control shaft, comprising:

• a first regulation part located in the engine body for mechanically regulating the control shaft to a position of maximum rotation on one side of a low compression ratio side and a high compression ratio side;
• and
• a second regulation part located in the housing for mechanically regulating the rotation shaft to a position of maximum rotation on the other side of the low compression ratio side and the high compression ratio side.