* Nikkei poised to post 2.8 pct gain this week
* Topix rises for 11th day, longest winning streak since May 2015
By Ayai Tomisawa
TOKYO, Nov 25 (Reuters) - Japan's Nikkei share average rose for a seventh straight session on Friday after U.S. shares soared and the dollar jumped further against the yen, lifting prospects for better corporate earnings.
The Nikkei rose 0.6 percent to 18,438.97 points by midmorning, extending its longest winning streak since November 2015.
For the week, the benchmark index is poised to rise 2.8 percent.
Meanwhile, the broader Topix was up 0.6 percent to 1,468.48, rising for an 11th day to post the longest winning streak since May 2015.
"Investors are chasing the market higher as the yen's weakness is continuing," said Kazuhiro Takahashi, an equity strategist at Daiwa Securities, adding that few people had expected that the yen would weaken this further.
The dollar was up 0.3 percent at 113.730 yen after hitting an 8-month high of 113.800 yen on rising U.S. bond yields.
Exporters staged a rally, with Toyota Motor Corp rising 2.4 percent, Honda Motor Co soaring 3.7 percent and Panasonic Corp surging 3.7 percent.
Banks were lower, with Mitsubishi UFJ Financial Group falling 1.9 percent, Mizuho Financial Group dropping 1.1 percent and Sumitomo Mitsui Financial Group shedding 1.4 percent.
For the next few weeks, traders said that investors are closely focused on a meeting of members of the Organization of the Petroleum Exporting Countries (OPEC) on Nov. 30 as well as Italy's referendum that could unseat Prime Minister Matteo Renzi early next month.
The JPX-Nikkei Index 400 gained 0.7 percent to 13,194.33. (Editing by Kim Coghill)