Paul Sheehan put together another solid round while capitalising on a final-round collapse by money leader Shingo Katayama to win the Japan Open by three shots on Sunday.

Sheehan, who had a one-stroke lead over Katayama at the start of the final round, closed with an even-par 71 that gave the Australian his third career victory on the Japanese tour on seven-under 206 at the Kasumigaseki Country Club.

Sheehan saw his lead widen to two shots with a front-nine 35 and briefly to four after a birdie on the 17th, which effectively assured him his first title in Japan following his victories in 2004 at the Fujisankei Classic and the Nippon Series JT Cup.

The 29-year-old earned Y40 million ($A446,880) out of the Y200 million ($A2.23 million) purse and a five-year exemption on the tour.

Azuma Yano matched Sheehan with a 71 and finished second at four-under 280.

Katsumasa Miyamoto, one of only five players who fired in the 60s on Sunday, and Takuya Taniguchi (73) followed a further shot back in a tie for third place.

Defending champion and second-round leader Katayama got off to a disastrous start by dropping three shots in the first four holes en route to a 3-over 75. He slipped into a five-way tie for fifth at 282.

"I feel great to win this prestigious tournament. I felt more pressure than I'd felt before and the course's setup was pretty tough today, but I'm fortunate I pulled it off," said Sheehan.

Sheehan set the tone for the rest of the day when he rolled in a delicate seven-footer for birdie on the par-3 fourth. After dropping a shot on the seventh, he parred the next nine holes and made his decisive birdie at No. 17 while his nearest pursuers struggled all afternoon in difficult course conditions.

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