A variable compression ratio apparatus is disclosed. An upper connecting rod has one end rotatably connected to a piston so as to reciprocate motion of the piston. A lower connecting rod has one end rotatably connected to the other end of the upper connecting rod. A crankshaft is rotatably mounted at an eccentric position of the lower connecting rod. A control rod has one end rotatably connected to the other end of the lower connecting rod, to control the position of that end of the lower connecting rod. A control shaft is connected to the other end of the control rod, to control the position of that end of the control rod.