The court, however, rejected publisher Takashi Asai's demand for government compensation of $20,370, Ando said. Asai, of Uplink publishers, had been fighting a 1999 confiscation of the book and his voluntary 2000 suspension of its sales after police warnings.
Mapplethorpe died of AIDS at age 42 in March 1989, but his images, including human bodies, sex and nudity, have remained controversial. High-profile opposition forced the cancellation of an exhibition of his work in Washington in 1989.
In Tuesday's ruling, Justice Kohei Nasu said the book of black-and-white portraits "compiles works from the artistic point of view, and is not obscene as a whole," the national Yomiuri newspaper reported.
The decision, a majority opinion of the five-judge bench, also recognized Mapplethorpe as "an artist who has won high appreciation as a leading figure in contemporary art," Kyodo News agency reported.
Asai called the ruling "groundbreaking" and said it "could change the obscenity standard" used for banning foreign films that show nudity and censoring photographs in books.
Asai had sold about 900 copies the Japanese version of "Mapplethorpe," which was originally published by Random House, in Japan starting in 1994 without objection from authorities.
But airport customs officials in Japan confiscated a copy he had with him when he returned from a trip to the U.S. in 1999. The 384-page book contained 20 close-up photos of male genitalia, and authorities considered it obscene.
Asai said he suspended sales of the Japanese edition in May 2000 after Tokyo Metropolitan Police summoned him and gave him a warning.
In 2002 he won a case in Tokyo District Court and the government was ordered to return the confiscated copy of the book and pay $6,480 in damages. But the high court overturned that ruling a year later.