The seasonally adjusted unemployment rate hit a nine-year low of 3.8 percent in April, down from 4.0 percent in March, the government said Tuesday, indicating an improving labor market amid the longest economic boom in the postwar period.

The jobless rate was the lowest since March 1998, when it also logged 3.8 percent, the Internal Affairs and Communications Ministry said in a preliminary report.

After hovering in a tight range of 4.0 to 4.2 percent for the 13th straight month since February 2006, the jobless rate finally slipped below 4.0 percent due mainly to an improvement in the labor market for younger people, a ministry official said.