Nippon Life Insurance Co. said Thursday it will start requiring all of its male employees who have babies to take at least one week of paternity leave.

In a rare step for a major Japanese firm, the country's biggest insurer said eligible workers are those with an infant who was born in October 2011 or later. They can start taking the leave the day after the baby is born, and must take the leave by the end of next March after the child turns 18 months old.

Out of Nippon Life's roughly 7,700 male employees, who make up about 10 percent of its workforce, about 280 were eligible for the leave as of the end of May.

"In general, it is hard for male employees to take child care leave (in Japan). We want to promote the trend of males taking the leave," said Hiromichi Ota, a spokesman for Nippon Life.

Just 2.63 percent of male workers at 4,097 polled firms took or planned to take child care leave in fiscal 2011, the Health, Labor and Welfare Ministry said. The poll didn't include disaster-hit Iwate, Miyagi and Fukushima prefectures.