Shoichi Nakagawa told parliament the meat was closely checked for banned material such as bone and brains when it entered the country. Japan halted imports again last week after it found banned spinal bones in a shipment of American veal.
Nakagawa said about 1,500 tons of U.S. beef has entered Japan since the easing of a two-year-old ban on Dec. 12. The ban was imposed in 2003 after the discovery of mad cow disease in an American herd.
Of those 1,500 tons, more than 700 tons have already been distributed to supermarkets, restaurants and other outlets, but Nakagawa said that meat posed no health risk.
"There is no worry about this beef already in circulation. Based on U.S. responsibility and Japanese rules, the proper procedures have strictly been taken to allow them into Japan," he said.
Still, Nakagawa said importers, restaurants and other businesses handling the meat should voluntarily check it for materials that are considered at risk of carrying mad cow disease.
The discovery of spinal bones in last week's veal shipment angered many in Japan, who accused the United States of sloppy compliance with the agreement that reopened the Japanese market.
Later Thursday, vice agriculture minister Mamoru Ishihara said Japan is considering limiting U.S. beef imports from about 10 facilities Japanese officials had inspected.
Tokyo dispatched a team of inspectors to 11 facilities in five states, Colorado, Kansas, Texas, Nebraska and California, among dozens of exporters in December, days after announcing the easing of an import ban.
Bovine spongiform encephalopathy, or BSE, is the medical name for mad cow disease, a brain-wasting disease in cattle. In people, eating meat or cattle products contaminated with BSE is linked to a rare, fatal human disease, variant Creutzfeldt-Jakob disease.