Japan's seasonally adjusted unemployment rate fell to 4.0 percent in May, down from 4.1 percent in April, its lowest level in eight years, the government said Friday.

The 4 percent jobless rate, a figure not seen since April 1998, beat the average market estimate of 4.1 percent, underscoring the steady improvement in the labor market.

The number of jobless totaled 2.77 million in the reporting month, down 300,000 from a year earlier, the sixth straight year-on-year decline, the Ministry of Internal Affairs and Communications said in a preliminary report.