This paper examines the time-varying relationship between the labor market, inflation, and monetary policy, particularly in light of recent high inflation and a tight labor market, with a focus on data from Korea. Analyzing data from July 2009 to June 2023, we find that the impact of the job vacancy rate — an indicator of labor market conditions — on inflation has gradually increased over time. Furthermore, the responsiveness of inflation to changes in labor market conditions is found to be greater during periods of high inflation compared to low inflation. Lastly, the influence of monetary policy changes on the job vacancy rate is particularly pronounced during recessionary periods and after the COVID-19 pandemic. These findings suggest the possibility of convexity in the relationship between the labor market and inflation in Korea. In such a scenario, raising interest rates during high inflation could lead to a relatively larger decrease in inflation than in job vacancies, which could create a favorable situation for monetary policy management.