TOKYO, March 22 (Reuters) - Japan's Nikkei share average hit a record high on Friday, underpinned by the strength on Wall Street overnight and as a weaker yen prompted investors to buy automakers.

The Nikkei rose to as high as 41,087.75 earlier in the session, crossing the 41,000 level for the first time. The index ended 0.07% higher at 40,844.53 by the midday break.

The Nikkei is on course for its fourth straight session of gains and, at current levels, is poised to jump 5.5% this week.

The broader Topix rose 0.44% to 2,808.58.

"The market had expected the yen would strengthen against the dollar in this quarter but that is not happening, which is positive for Japanese firms," said Shuji Hosoi, senior strategist at Daiwa Securities.

"The yen remains weaker as Japanese (government bond) yields are not expected to rise sharply. The Bank of Japan said it would keep its easy policy so the gap in yields between the U.S. and Japan will not narrow."

BOJ Governor Kazuo Ueda on Thursday vowed to keep supporting the economy with ultra-loose monetary policy, in fresh comments after the central bank ended eight years of negative interest rates and other remnants of its unorthodox policy on Tuesday.

The yen fell after the BOJ's historic policy shift and was last a whisker from multi-year lows at 151.58 per dollar.

A softer yen helps exporters as it increases the value of overseas revenue in yen terms when firms repatriate them to Japan.

Toyota Motor rose 1.87% to become one of the biggest boosts to the Nikkei. Suzuki Motor jumped 3.57%.

The index for automakers rose 1.62%.

Tyre makers jumped 2.28%, the most among the Tokyo Stock Exchange's 33 industry sub-indexes.

Chip-related Advantest slipped 2.43% and Tokyo Electron lost 0.31%. (Reporting by Junko Fujita; Editing by Savio D'Souza)