* Exporters gain ground as yen weakens
* Nikkei regains ground lost after missile caused a 4-mth low
TOKYO, Aug 30 (Reuters) - Japan's Nikkei share average on Wednesday recovered all of the previous day's loss, helped by Wall Street's rise and a weaker yen, as worries sparked by North Korea firing a missile over Japan receded.
The Nikkei, which on Tuesday hit a fourth-month low and ended 0.5 percent down, climbed 0.7 percent to 19,506.54.
North Korea's launch of a ballistic missile over Hokkaido island into the sea on Tuesday had triggered steep losses in the market, sending the Nikkei to the lowest since May 1.
Traders said North Korea-related concerns may persist and the Nikkei may fall 100-200 points if there is another missile test. But they added that such concerns can fade when stock valuations become cheap and investors hunt for shares of firms with a strong outlook.
"Yesterday's incident is considered to be one of those threats by North Korea. Unless there is military action taken by either North Korea or the United States, the market will likely rebound quickly," said Toru Ibayashi, executive director of wealth management at UBS Securities in Tokyo.
Exporters gained ground after the dollar last traded at 109.85 yen, having recovered from Tuesday's low of 108.265 yen, which was the greenback's lowest level since mid-April.
Hitachi Ltd gained 2.8 percent, Panasonic Corp added 0.8 percent and Keyence Corp rose 1.5 percent.
Dunlop Sports jumped 15 percent after the sports goods maker said it would merge with Sumitomo Rubber Industries .
The broader Topix gained 0.6 percent to 1,607.65. (Editing by Richard Borsuk)