* Ex-dividend adjustments seen around 130 points
* Topix volume lowest since August 2012
* Toyota, Nissan, Mizuho FG lower
TOKYO, Sept 27 (Reuters) - Japanese stocks fell to 1-1/2-week lows on Wednesday as ex-dividend share price adjustments dented high yielders such as automakers, offsetting gains in tech firms which tracked strength in their U.S. counterparts.
The Nikkei dropped 0.3 percent, or 63.14 points, to 20,267.05, the weakest level since Sept. 15, moving away from a two-year high of 20,481.27 hit last week.
About 130 points were cut from the Nikkei by the ex-dividend price adjustment, according to market participants. High-yielding stocks including automakers, railway operators as well as banks and securities firms underperformed.
"The Nikkei would have been stronger today without an ex-dividend effect," said Yutaka Miura, a senior technical analyst at Mizuho Securities. "The Japanese market's sentiment itself is positive helped by a weaker yen after Yellen's comments."
U.S. Federal Reserve Chair Janet Yellen said the Fed needs to continue gradual rate hikes despite uncertainty about the path of inflation.
The dollar was at 112.27 yen, bouncing back from Tuesday's low of 111.50.
The broader Topix shed 0.5 percent to 1,664.43. Volume was thin, with only 1.2 billion shares changing hands, the lowest level since August 27, 2012.
Toyota Motor Corp dropped 1.0 percent, Nissan Motor Co shed 2.6 percent, West Japan Railway Co declined 1.9 percent, while Mizuho Financial Group fell 1.4 percent and Daiwa Securities Group tumbled 1.7 percent.
Some tech shares outperformed the overall market, with Advantest Corp surging 2.0 percent and Panasonic Corp gaining 0.8 percent.
Elsewhere, agricultural chemical maker Nihon Nohyaku tumbled 4.3 percent after it cut its operating profit outlook to 3.1 billion yen from its previously forecast 3.9 billion yen for the year ending September. (Editing by Shri Navaratnam)