This paper investigates the impact of a minimum wage increase on the number of vacancies and job seekers using data from Japan's public employment placement service. The results show that for 2005-2019, a rise in the minimum wage reduced the number of vacancies. On the other hand, it increased the number of job seekers and then decreased the vacancy-job seeker ratio. Some part of this came from the increased job separation into unemployment. The impact of a minimum wage rise is conspicuous during the period of the slack labor market, for prefectures with high Kaitz indices or with a high proportion of small firms, and part-time jobs..