In this paper I have focused on the theory of about Performance Interest (Expectation Interest) and reliance interest. The Supreme court decided that plaintiff might claim Performance Interest (Expectation Interest) or Reliance Interest alternatively. I have agreed to the theory of the Supreme Court Decision I have analysed the basis on the law of contract that belongs to damages as the object to have to compensate. Recently it has been admitted reliance interest by the Supreme Count. This means that admitted cases offer a clue to insist on the theory that damages should be compensated by reliance interest against expectation. I hope that provisions regarding compensation of the disbursement of expenses shall be stipulated in Article 393 paragraph③ of the Korean Civil Code like Article 77 in CISG or Article 284 in BGB.