Merger between financial institutions is accomplished through business judgement of each company subject to commercial law, competition law, securities law and other relevant laws. For financial institutions, merger activities are additionally restricted by financial laws and regulations due to its public nature and impact on the national economy. For above reasons, the Financial Services Commission has the ultimate authority to approve the merger of financial institutions. Most cases of domestic mergers among financial institutions are achieved according to the Act on the Structural Improvement of the Financial Industry ("Geum San Bup") due to expeditious merger process, tax benefit and diverse legal support. Despite of these merits, stockholders and creditors of the merging institutions cannot be given the procedural rights properly. Therefore, application of the provisions for expeditious merger process needs to be limited to merger cases involving insolvent financial institutions. Availability and accessibility of financial services should be sufficiently guaranteed to the affected personal customers and small/middle sized business in case of mergers of financial institutions. Contribution to global competitiveness, employment and innovation in finance industry should also be considered as one of the public interest factors. Merger between financial institutions expands size of the bank, which increases credit and systemic risk in financial industry. For this reason, financial authority needs to pay attention not only to loss absorption capability of the big bank but also to measures of safeguarding asset of depositors and customers. Cooperation between organizations is crucial in order to analyze the impact of mergers on customers, financial industry and national economy. Bank of Korea, Korea Deposit Insurance Corporation, consumer protection organizations and Fair Trade Commission should evaluate merger based on its own function and suggest corrective measures to set off the problems caused by merger. Modification of information related laws should be established in order to protect the right of customers with respect to personal and credit information, as well.