The two executions for multiple murders bring to 14 the total number of death sentences carried out since Prime Minister Shinzo Abe took power in late 2012.
Sumitoshi Tsuda, 63, was hanged for killing three people in the city of Kawasaki, near Tokyo, in May 2009, a justice ministry official said.
It was Japan’s first execution of a death row inmate sentenced by so-called lay judges, Japanese media reported.
Japan in 2009 launched a jury system in which citizens deliberate with professional judges in a bid to boost the role of the citizenry in the judicial process.
Under the system, a total of 26 people have been sentenced to death, according to public broadcaster NHK.
“Lay judges made the very grave judgement and I took it seriously,” Justice Minister Mitsuhide Iwaki told a news conference.
Separately, Kazuyuki Wakabayashi was executed for killing two people, including a 52-year-old mother, in 2006 in Iwate, northern Japan, the ministry official said. The 39-year-old was sentenced to death by professional judges.
Japan and the United States are the only major advanced industrial nations that continue to have capital punishment.
Surveys have shown the death penalty has overwhelming public support in Japan, despite repeated protests from European governments and human rights groups.
International advocacy groups say Japan’s system is cruel because inmates can wait years for their executions in solitary confinement and are only told of their impending death a few hours ahead of time.
Before today’s executions Japan had 128 inmates on death row, according to local media.