Japan's unemployment rate improved to 4.0 percent in the year of 2013 from the reading of 4.3 percent in 2012, marking the third straight year of improvement, according to the Japanese internal affairs ministry Friday.

The ministry said in a preliminary report that jobless people decreased by 200,000 from 2012 to 2.65 million in 2013, as those quitting jobs involuntarily dropped by 120,000 to 900,000.

Meanwhile, the country's jobless rate in December improved to 3. 7 percent from the previous reading of 4.0 percent logged in November 2013, the lowest level in six years, said the ministry.

Separated data showed Friday that the country's job availability hit its highest level since September 2007 to 1.03 in December, up 0.03 from November's 1.00, meaning that 103 positions were available for every 100 job seekers.

The ratio improved by 0.13 percentage point from 2012 to 0.93 in last year, said the country's labor ministry.