The Act on Liability for Environmental Damage and Relief Thereof has contributed to improve the way of protecting victims of environmental damage by specially recognizing the presumption of casual relationship and risk liability of a business owner while mainly focusing on liability for compensation on environmental damages. As a requirement for asking liability for compensation to a business owner who operates a facility, ① pollutants are occurred in relation with installation and operation of a certain facility, ② these pollutants cause environmental degradation, and ③ all these bring damages. And, the casual relationship is presumed and No-fault liability of the business owner is specified. In particular, this study reasoned discussions on regulations regarding presumption of casual relationship and no-faulty liability of the business owner who takes the responsibility for facility operation. The paramount challenge during the process of legal relief of environmental damages is how to prove the casual relationship between harmful acts and damage occurrence. To resolve the difficulties of proof, the Article 9 prescribes the presumption of casual relationship. However, there is an argument that the presumption in the Article 9 is not de-jure, but de-facto. It is asked to check. Reviewing the burden of proof in the Article 9 in line with the burden of proof theory, if a victim of environmental damage could prove the casual relationship like general illegal activities or ‘It is highly probable to believe that a facility has caused environmental damage exists’ (prerequisite), the casual relationship that the facility causes environmental damage is presumed (presumed fact). Meanwhile, the presumption could be reversed when the business owner of the facility which is the attacker is not a cause of the environmental damages: the burden of proof could be converted in terms of the meaning that the attacker takes the burden of proof for the non-existence of presumed fact. In addition, presumption by law has an effect of converting the burden of proof to the other party. To broke the de jure presumption, disproof is not enough. The counterexample should be proved so the process by the attacker to clarify the non-existence of the presumed fact could be ‘Proof’ Lawsuit on environment has adopted contingency theory for the precedent regarding the presumption of the cause and effect relationship. However among precedents, the decision on the probability could have difference in line with the individual cases. Due to this fact, in accordance with Article 9, Paragraph 1, in regards to the prerequisite of the presumption of the casual relationship on environmental damages, it specifies ‘sufficient probability’, not ‘probability’ like precedent. Moreover, the Article 9, Paragraph 2 suggests detailed standards on the sufficient probability. It is that this act has more detailed requirement than that of three stage requirement to recognize the case and effect relationship in line with the probability theory acknowledged by existing precedents. Accordingly, it is hard to translate that the sufficient probability specified in Article 9, Paragraph 1 is literally legalize the probability theory recognized by the existing precedent when reviewing this with the standard of sufficient probability prescribed in Article 9, Paragraph 2. In this respect, it will be desirable to use the term ‘Facility Suitability’ like German Environment Liability Act, Article 6 rather than using uncertain term, Sufficient Probability in Article 9, Paragraph 1. In Korea, danger liability is understood as the same one with no-fault liability. However, this study doubt it. No-fault liability and danger liability is not the same concept and the both terms are clearly differentiated conceptually. Furthermore, the notion of danger liability and no-fault liability is clearly distinguished. It is common that danger liability and no-fault liability do not require damages. danger liability is not illegal liability but faults on the allowed risky factors so not requiring illegality but no-fault liability imposes liabilities even without fault on the premise of illegal activities. Accordingly, it is fare to understand that danger liability and no-fault liability are toally different concept.