In this case, the insurer mistakenly wrote policies that can be interpreted as a meaning of ‘in case of suicide, accidental death benefit can be paid according to accidental death rider.’ Precedents on this case are different. Some courts rule out that the insurance company should pay the proceeds, because the insurer, as an expert, should be responsible for mistakenly writing the policies, even though suicide itself is not a disaster. By contrast, others contend that the responsibility for provision of the insurer do not exist, since suicide cannot be included among the category of disaster regarding its properties. Supporters of this opinion claim that in case of common client, it should be concluded that the client would have fully understood that accidental death benefit would not be paid in case of suicide during the process of agreement. Like this case, if insurance policies are mistakenly written and became part of insurance contracts, both general principles of contract interpretation and general principles of policy interpretation should be applied, in order to draw reasonable interpretation. In the process of establishing an insurance contract, key provisions of the insurance policy must consider whether insurance contract parties reach consensus. Other provisions of the insurance policy are considered in a comprehensive perspective. After the establishment of insurance contract, insurance policies would be regulated by the general principles of policy interpretation. When interpreting insurance contracts, the point that the client cannot choose whether the one would make the contract without any practical process of negotiation, about the contract that includes insurance policies that are written solely by the insurer should be considered. Meanwhile, interpretation of insurance policies should be done systematically and logically based on common client’s possibility of understanding. Accordingly, conclusion of this case can be differed by how do we comprehend the common client’s level of understanding.