TOKYO (Kyodo) -- The Nikkei stock index ended at a five-month high above 40,000 on Friday, as a weaker yen boosted automakers and other export-oriented issues on hopes of greater profits.

The 225-issue Nikkei Stock Average closed up 713.10 points, or 1.80 percent, from Thursday at 40,281.16, its highest level since July 17. The broader Topix index finished 34.90 points, or 1.26 percent, higher at 2,801.68.

On the top-tier Prime Market, gainers were led by electric power and gas, service, and iron and steel issues.

The U.S. dollar stayed mostly firm in the upper 157 yen range in Tokyo, as the yen remained under pressure on speculation that the Bank of Japan will be cautious about additional interest rate hikes.

At 5 p.m., the dollar fetched 157.81-83 yen compared with 157.97-158.07 yen in New York and 157.35-37 yen in Tokyo at 5 p.m. Thursday.

The euro was quoted at $1.0421-0423 and 164.46-50 yen against $1.0417-0427 and 164.64-74 yen in New York and $1.0396-0398 and 163.59-63 yen in Tokyo late Thursday afternoon.

The yield on the benchmark 10-year Japanese government bond rose to 1.110 percent during after-hours trading, up 0.025 percentage point from Thursday's close and the highest since July 2011, as investors sold the safe-haven debt on rising Tokyo stocks. In regular trading hours, the yield ended at 1.100 percent.

On the equities market, the Nikkei index climbed 2 percent at one point as auto and electronics issues were sought on the weak yen, which lifts their overseas profits when repatriated.

"The weak yen is working positively not only for manufacturers but also companies with a strong overseas presence, mainly in the United States," said Maki Sawada, a strategist in the Investment Content Department of Nomura Securities Co.

Investors were also reassured by a summary of opinions from last week's Bank of Japan policy meeting, which brokers said aligned with the central bank's recent cautious approach to further interest rate hikes.

A wide range of issues were sought as overseas investors returned to the market after the Christmas holiday, analysts said.