A variable compression ratio apparatus may include a connecting rod provided with one end formed of a mounting hole and the other end eccentrically and rotatably connected to a crankshaft, wherein a piston pin may be inserted in the mounting hole and the connecting rod may be rotatably connected to the piston through the piston pin, an eccentric link provided with an eccentric bearing concentrically and rotatably mounted in the mounting hole may be connected and, the piston pin being eccentrically and rotatably mounted in the eccentric bearing, a variable link pivotally connected to the eccentric link, a variable gear link pivotal with respect to a fixed shaft and having a first gear teeth at an exterior circumference thereof, an external circumferential portion thereof being rotatably connected to the variable link, and a control shaft formed of a second gear teeth engaged to the first gear teeth.