Shizuka Kamei, former policy chief of the ruling Liberal Democratic Party, and seven other lawmakers belonging to a group opposing capital punishment have asked Justice Minister Mayumi Moriyama not to carry out any further executions.
Kamei, head of a group comprising 74 Diet members, noted Tuesday that South Korean lawmakers recently submitted a bill to the South Korean parliament to abolish the death penalty.
"We question the existence of the death penalty amid the possibility of wrongful convictions," he said.
"Even if the (capital punishment) system exists, we want you to stop executions for the meantime."
Moriyama said, "It is a very difficult thing, but I would like to think about it carefully."
No death-row inmate has been executed in Japan for more than a year. Three were hanged in November 2000.
Death sentences are often carried out shortly after Diet sessions close, and the appeal by Kamei's group came just ahead of the end of the current Diet session Friday.
Kamei, a former senior official at the National Police Agency, said capital punishment is wrong because of the possibility of erroneous convictions.
He also said the justice system depends too much on confessions and that judges place too much trust in police and prosecutors.
The Diet group was formed in April 1994 by lawmakers from both the ruling and opposition camps, and Kamei is the fourth politician to lead it. He became the head of the group on Nov. 2.