TOKYO — In a move heavy with symbolism for Japan’s workaholic fathers, Shinjiro Koizumi, a politician seen as a possible future prime minister, said on Wednesday that he would step back from his duties to care for his newborn child after the birth later this month.

By the standards of other wealthy countries, Mr. Koizumi, Japan’s environment minister, will not be away from work for long. He will take a total of two weeks of paternity leave spread over three months, during which he will work flexibly from home or put in fewer hours.

But in Japan, where fathers who take time off after a birth are rare, word of Mr. Koizumi’s intentions swept social media and drew praise from supporters as setting a powerful example.

“I hope my taking paternity leave will lead the way of working styles to one where everyone can easily take child-care leave without hesitation in the environment ministry,” Mr. Koizumi, 38, said in a meeting with his staff on Wednesday.