A variable compression ratio apparatus mounted on an engine configured to receive combustion force of a mixer from a piston to rotate a crankshaft, and configured to change a compression ratio of the mixer may include an eccentric bearing assembly connected with the piston through a piston pin, and including an eccentric ring including an eccentric hole through which the piston pin passes so that the piston pin may be rotatably installed while being eccentric to the eccentric ring, and an eccentric link connected to the eccentric ring to transfer rotation force thereof to the eccentric ring, a connecting rod including one end provided with a mounting hole into which the eccentric ring may be rotatably inserted, a central portion provided with an operation hole, wherein the eccentric link may be movable through the operation hole, and the other end rotatably connected to the crankshaft while being eccentric to the crankshaft, and a control shaft connected to the eccentric link and configured to rotate the eccentric bearing assembly.