In the Kyoto District Court ruling, Presiding Judge Hitoshi Hashizume said the language that members of the anti-Korea group Zaitokukai and their supporters shouted and printed on banners during rallies in 2009 and 2010 was illegal, and had disturbed classes and scared the students. The judge said that posting video footage of the rallies on the Web was illegal.
He said the rallies "constitute racial discrimination" defined under the United Nations' convention on the elimination of racial discrimination, which Japan has ratified.
Monday's ruling banned the group from staging further demonstrations in the neighborhood of the pro-Pyongyang Korean elementary school in southern Kyoto, according to court spokesman Naoki Yokota.
Later Monday, Chief Cabinet Secretary Yoshihide Suga said he was "concerned that similar hate speech rallies might have been disturbing store operations and school classes." Suga promised to take proper actions against the problem by law, but did not elaborate if the government would consider new hate speech legislation.
Arita said he hoped the ruling would put a brake on such hate speech rallies elsewhere in Japan.
Ikuo Gonoi, an associate professor Takachiho University In Tokyo who researches democracy and demonstrations, said legal restrictions on hate speech need to be carefully considered so the government won't use them arbitrarily to restrict freedom of speech.
There are about 500,000 Koreans in Japan the country's largest ethnic minority group and many are descendants of forced laborers shipped to Japan during its 1910-1945 colonial rule of Korea. They still face discrimination in education, marriage and jobs.
Anti-Korean rallies have escalated this year and spread to other cities with Korean communities. In Tokyo's Shin-Okubo district, dotted with Korean restaurants and shops popular among South Korean pop-culture fans, hundreds of Zaitokukai members and supporters have called Koreans "cockroaches," shouted "Kill Koreans" and threatened to "throw them into the sea."
The rallies have grown more intense, with anti-racism activists yelling back and sometimes getting into scuffles. In June, Zaitokukai leader Makoto Sakurai and seven others from both sides were arrested.
Officials from Zaitokukai, which has more than 10,000 members, said they were protesting the Kyoto school's use of a nearby city-run park without permission. They say they are protesting alleged "special privileges" given to ethnic Koreans, and say Japan's welfare system is abused by Korean residents.
"Saying 'Let's kill Koreans' isn't illegal, so it's OK to say that. We've kept quiet for too long and we've had enough," Sakurai told The Associated Press at a rally earlier this year. "Koreans hate us so much so we just tell them to go home. Call us racists if you want."
Shinichi Tokunaga, a lawyer for the group, criticized the ruling Monday for restricting political expression.
The school filed the lawsuit in June 2010 against the group and eight activists over rallies held on three occasions between December 2009 and March 2010. The activists threatened Koreans and called them names, causing some children to develop stomach pains, the lawsuit said.
Human rights experts say Zaitokukai and its sympathizers have intensified their campaign since the Liberal Democratic Party of nationalist Prime Minister Shinzo Abe returned to power last December.
During a parliamentary session in July, Abe called the group's activities "regrettable."