Tokyo stocks opened lower Monday as the yen's appreciation against the U.S. dollar dented investor sentiment and weighed on exporter issues.

As of 9:15 a.m., the 225-issue Nikkei Stock Average lost 176.51 points, or 0.88 percent, from Friday to 19,923.24.

The broader Topix index of all First Section issues on the Tokyo Stock Exchange, meanwhile, dropped 14.95 points, or 0.92 percent, to 1,615.04.

All industry categories on the main section retreated into negative territory, with mining, rubber product and bank-linked issues comprising the most notable decliners in early trade.