When the breach of contract is at issue between the contracting parties, the decision of the contents of obligation has an important meaning. The contents of obligation is decided by the construction of cont-ract. Therefore, the construction of contract has very important meaning for the decision of the contents of obligation. And the Civil Law of Korea includes provisions to settle disputes related to contract, and most of these provisions have the nature of voluntary law. And when there is no intention of the contracting parties, or it is not clear, the voluntary law comes into application(Civil code art. 105). Ultimately, voluntary law not only becomes the standard of the construction of the contract, but also it is applied as the law to settle dispute. Thus, it needs to clear what is the relation between the construc-tion of contract and the application of law. Therefore, this paper aims to clarify the relationship between the construction of contract and the appli-cation of law.