A Warner Bros. spokeswoman in Tokyo said British actor Daniel Radcliffe, who plays the broomstick-flying Harry, would come to Tokyo for the event, which is scheduled ahead of the movie's London showing on July 3.
"Harry Potter and the Order of the Phoenix" is the latest installment in a series that began in 2001 with "Harry Potter and the Sorcerer's Stone."
The four previous "Harry Potter" movies, based on J.K. Rowling's books, have grossed more than $3.5 billion worldwide.
There is "no special reason" why the film is making its premiere in Japan, the spokeswoman said.
But the Tokyo premiere last month of another highly anticipated sequel, "Spider-Man 3," was seen as a shrewd push into the faster-growing international market that could help boost box-office revenues.
The seventh and final book in the "Harry Potter" series, "Harry Potter and the Deathly Hallows," will go on sale on July 21, but it is not clear when the film version will be made.