Japan's benchmark Nikkei stock index, the 225-issue Nikkei Stock Average, ended down 674.05 points, or 1.77 percent, from Friday at 37,388.62.
The broader Topix index, meanwhile, finished 37.46 points, or 1.40 percent, lower at 2,641.14.
The U.S. dollar weakened to a two-week low in the 145 yen zone on Monday in Tokyo on selling fueled by speculation that U.S. labor data could be revised down this week.
Market watchers here noted that Tokyo stocks largely traded lower under pressure from the Japanese currency's upward trend. A firm yen reduces the overseas profits of exporters when repatriated.
On the top-tier Prime Market, decliners were led by mining, machinery and transportation equipment issues.
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