This study aims to examine present working conditions of the part-time workers and analyse the causes of unfavorable situations of them in spite of the policy efforts by the government in Korea. Unlike existing researches focused on policy failures, this study take note of the institutional accordance/discordance between Korean labor market institutions and the necessary conditions to create qualified part-time jobs. The results are following. First, part-time workers in Korea are on the most disadvantageous working conditions even compared to temporary or atypical workers. Second, the reason of the disadvantageous working conditions is that most part-time jobs are created from the service sector SMEs, which have low productivity and lousy working conditions. Third, employers in the primary labor market tend to refuse to create qualified part-time jobs because of their skill-saving production systems, alternative ways to gain numerical labor flexibility, absence or lack of external pressure from the labor or state, and long working-hour labor culture. To improve labor market institutions and create qualified part-time jobs, it is necessary to reorient the current part-time work policy from support for private employers to guarantee of workers’ rights. Furthermore, comprehensive labor market institution reform is required beyond policies limited to part-time employment.