The meaning of Good faith is honest intent to act without taking an unfair advantage over another person or to fulfill a promise to act, even when some legal technicality is not fulfilled. The term is applied to all kinds of transactions. According to the CISG only regulated Art. 7. that is in the interpretation of this Convention, regard is to be had to its international character and to the need to promote uniformity in its application and the observance of good faith in international trade (1) and questions concerning matters governed by this Convention which are not expressly settled in it are to be settled in conformity with the general principles on which it is based or, in the absence of such principles, in conformity with the law applicable by virtue of the rules of private international law (2). In the other hand PICC is related to the good faith and fair dealing, each party must act in accordance with good faith and fair dealing in international trade (1) and the parties may not exclude or limit this duty (2). Good faith of PECL is these principles should be interpreted and developed in accordance with their purposes. In particular, regard should be had to the need to promote good faith and fair dealing, certainty in contractual relationships and uniformity of application. Further more regarding to the good faith and fair dealing, same to the PICC regulations.