The House of Councilors on Friday voted overwhelmingly in favor of allowing members who are about to give birth to be officially excused from attending the legislature.
Only one member, Michio Sato of the Niin Club-Jiyurengo parliamentary alliance, voted against the provision, which would revise the conditions under which Upper House members can be legitimately absent from Upper House sessions.
With the vote, childbirth will join official business, illness and accidents as legitimate reasons allowing members to be absent.
The proposal was promoted by a nonpartisan group of female members of the house.
The legislature's lack of provisions for maternity leave was brought to light by the recent pregnancy of Seiko Hashimoto, an Upper House member belonging to the ruling Liberal Democratic Party.
"This is the first step in helping the Diet to catch up with trends in the private sector," Hashimoto said shortly after the measure was passed. "There should be child-care centers (in the Diet) too, which is something I would like to work toward."
Sato, however, questioned whether the revision would find support among the public.
"The work of Diet members is a serious matter and people holding such a position need to be aware of that," he said. "If (female) heads of municipalities, Cabinet ministers or prime ministers were to ask for maternity leave, what would the public think?"
In the House of Representatives, meanwhile, the LDP has proposed holding talks on introducing the same provision, but the proposal has failed to materialize.