Singh, who began the day tied for the lead with Tetsuya Haraguchi, made five birdies and a bogey en route to a 16-under 272 at the Kuroshio Country Club.
New Zealand's David Smail had a 68 and finished second, two strokes back. Shingo Katayama (68), who has clinched his third straight money title, and Haraguchi (72) shared third with Toshinori Muto (70) and Lin Keng-chi of Taiwan (69).
On Friday, Michelle Wie missed the cut after an 80 left her at 17-over 161.
Singh's victory followed his win at the Volvo Masters on the European Tour and runner-up finish at the Asahi Ryokuken Yomiuri Memorial last month.
Singh had been winless in his six years on the Japanese circuit.
Copyright 2006 Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.