TOKYO — In Japan’s largest antinuclear rally since the disaster at Fukushima, tens of thousands of protesters gathered at a park in central Tokyo on Monday to urge the government to halt its restarting of the nation’s reactors.

Organizers said 170,000 people filled a Tokyo square to sing songs, beat drums and cheer on a series of high-profile speakers who called for more Japanese to make their voices heard. The police put the number at 75,000, still making it the biggest gathering of antinuclear protesters since the Fukushima accident last year.

“To stay silent in the wake of Fukushima is inhuman,” the Oscar-winning musician Ryuichi Sakamoto told the crowd, which braved soaring temperatures to gather at Yoyogi Park.

Polls suggest that public opinion is still divided over the future of nuclear power in Japan. But a unilateral decision last month by Prime Minister Yoshihiko Noda to start putting the country’s reactors back into use has angered many Japanese and galvanized the antinuclear camp.