* Toshiba jumps on short-covering
* China economy and Fed policy dominate investors' minds - analyst
* Market focused on foreign visitors data for July due out at 0500 GMT
By Ayai Tomisawa
TOKYO, Aug 19 (Reuters) - Japanese stocks fell on Wednesday morning after Wall Street retreated on earnings woes and China concerns, while Toshiba Corp jumped after announcing a new board to improve corporate governance.
Toshiba soared as much as 7.3 percent and was the third most traded stock by turnover. Traders said that investors believe the worst is over for the company after it proposed a new board dominated by outsiders, which it hopes will help to reform the conglomerate after a $1.2 billion accounting scandal.
In midmorning trade, the Nikkei share average shed 0.5 percent to 20,446.09.
U.S. stocks dropped overnight partly on a decline in commodity stocks on concerns about China's economy.
"Investors care about these two things - China's economy and the timing of a U.S. rate hike. These two concerns dominate their minds now," said Masaru Hamasaki, head of market & investment information department at Amundi Japan.
"If China's economy slows down, it will affect other countries' exports including Japan's."
Earlier on Wednesday, data showed Japan's exports growth to China, its largest trading partner, slowed to 4.2 percent on-year in July, from 5.9 percent in June.
Most exporters were lower, with Toyota Motor Corp falling 0.2 percent and Canon Inc dropping 1.0 percent.
Nojima Corp tumbled 19 percent after the electronics retail shop operator said it will raise about 15 billion yen through new shares and over allotment.
Markets were also looking to the release of July foreign visitors to Japan by the Japan National Tourism Organization at 0500 GMT.
Stocks related to inbound tourism such as Isetan Mitsukoshi Holdings, Don Quijote Holdings and Shiseido Co may be bought if the numbers are strong, traders said. During the first half of this year, a record number of foreigners travelled to Japan, up 46 percent on year to 9.14 million, the organization said last month.
The broader Topix dropped 0.6 percent to 1,662.44 and the JPX-Nikkei Index 400 declined 0.6 percent to 14,971.13. (Editing by Shri Navaratnam)