1. In the so-called “Continuing guarantee” to guarantee an uncertain obligation arising from a continuous transactional relationship, where the circumstance at the time of the formation of the guarantee agreement is deemed to have been significantly changed and the obligation to guarantee the guarantor continues to be not reasonable in light of the parties’ intent and the good faith principle, the guarantor may terminate the guarantee agreement by either unilateral declaration of intent to terminate the guarantee agreement, barring special circumstances, such as where the other party’s creditor suffers losses which cannot be impliedly determined in light

Therefore, in a case where a person who has become a joint and several surety for a company's obligation arising from a continuous transaction between the company and the bank inevitably retires from the company and loses his position as a director, it is improper to maintain the status of a joint and several surety by social norms. Thus, it is unreasonable to unilaterally terminate the joint and several surety contract on the ground that a significant change occurs in the situation at the time of the establishment

(See Supreme Court Decisions 92Da2332 delivered on May 26, 1992; 99Da61750 delivered on March 10, 200, etc.). 2. According to the reasoning of the first instance judgment as cited by the lower court and the evidence duly admitted, the following facts can be revealed.

On September 24, 2012, the Plaintiff entered into a credit transaction agreement with “A” corporation (hereinafter referred to as “A”) and “A” corporation’s loan for corporate purchase. The credit limit amount is KRW 500 million from September 24, 2012 to September 24, 2013.

B. On September 24, 2012, the Defendant: (a) determined the amount of guarantee limit on the extension of service on September 24, 2012 as KRW 600 million; and (b)