Japan's unemployment rate hit a 45-month low of 4.6 percent in May, down 0.1 percentage point from April, with the largest margin of improvement in the jobless number on record, the government said Tuesday.

The number of jobless people totaled 3.19 million in the reporting month, down 560,000 from a year earlier, the best improvement since comparative data were made available in 1953, the Ministry of Public Management, Home Affairs, Posts and Telecommunications said in a preliminary report.

The unemployment rate, the lowest since August 2000, also beat the average private-sector projection of 4.7 percent, marking the 12th straight month of year-on-year decline.