Suspected rightists hurled two Molotov cocktails into the grounds of Fuji Xerox Co. Chairman Yotaro Kobayashi's home in Meguro Ward, Tokyo, over the weekend.
The Metropolitan Police Department said Tuesday that Kobayashi, 71, was on a business trip abroad at the time. None of his family members was injured.
The MPD said it suspects that rightists were involved because a group of nationalists waged a series of loudspeaker campaigns around Kobayashi's home last year.
Kobayashi heads a group of experts from both China and Japan that is discussing the improvement of bilateral relations. In September, he criticized Prime Minister Junichiro Koizumi for his repeated visits to Yasukuni Shrine in Tokyo, which honors the nation's war dead as well as Class-A war criminals.
The visits have angered parts of Asia that were victims of Japan's wartime aggression, especially China.