This article attempts to describe and analyze discussions on the matter of ex tunc effect or a ex nunc effect of rescission under Korean law in comparison with those under the CISG). In addition, it tries to scrutinize the various rules on the right to damages as an effect of rescission in a comparative way. Furthermore, it compares the various rules of Korean law with the CISG as to the right to damages and evaluates them in light of the discipline of comparative law. It maintains that the liquidation theory in Korean law is more close to the CISG in that there is no ex tunc effect in rescission and in other aspects. It also argues that the construction of the effects of rescission in accordance with the liquidation theory is more plausible when one considers Korea is one of the contracting states of the CISG. In addition, the theoretical analysis and the comparative study with the CISG shows that the insistence of ex nunc effect and its interpretation on the scope of damages extends to damages for expectation interest. It is also submitted that the position under the CISG on the assumption of ex nnuc effect, is regretted in that the restitution in value of the goods in the event of impossibility of the physical restitution is not allowed in some cases which the damage claims can not be awarded for the seller due to the application of the CISG Art. 79.