TOKYO, Feb 14 (Reuters) - Japan's Nikkei share average slipped to a one-week low in volatile trade on Friday, giving up earlier gains as sentiment was soured by a stronger yen and as some investors trimmed their exposure ahead of the weekend. The Nikkei ended down 1.5 percent at 14,313.03, the lowest closing level since Feb. 6 after rising as high as 14,678.71. It dropped 1.0 percent for the week, marking the sixth straight weekly fall. As U.S. markets are closed on Monday for a holiday, traders said that foreign investors did not want to hold onto big positions before a long weekend. The broader Topix shed 1.3 percent to 1,183.82. The JPX-Nikkei Index 400, an index launched this year comprised of firms with high return on equity and strong corporate governance, dropped 1.3 percent to 10,711.29.