TOKYO, May 19 (Reuters) - Japan's Nikkei share average ended little changed on Thursday, moving in and out of positive territory as general caution offset some gains from Federal Reserve minutes that boosted the dollar and weakened the yen.
Some investors stayed on the sidelines ahead of Group of Seven meetings to be held this week in Japan.
The Nikkei ended flat at 16,646.66.
Oil shares' drops weighed after oil prices fell, pulled down by rising U.S. crude inventories, a stronger dollar and surging output from Iran to Europe and Asia.
Inpex Corp stumbled 5.9 percent and Japan Petroleum Exploration Co dived 4.6 percent.
The broader Topix edged down 0.1 percent to 1,336.56 and the JPX-Nikkei Index 400 declined 0.2 percent to 12,086.37. (Reporting by Ayai Tomisawa; Editing by Richard Borsuk)