The governments of almost countries have the rules and procedures that the purchasing entities have to follow, in order to ensure that the best value for money spent is obtained in procuring goods and services. However, there are often some of important problems in their rules relating to government procurement. Namely, almost countries have a variety of discriminatory regulations for foreign suppliers in the government procurement laws with the object of national security, economic welfare, and protection of domestic market from international competition. For this reason, several advanced countries had reached the Plurilateral Agreement on Government Procurement during Tokyo Round(1973-1979) and Uruguay Round(1986-1994). However, the provisions of two agreements do not apply to all products made by the government but only to those made by purchasing entities specified by each member country in its list in the Appendix. Accordingly, the size of goods and services purchased from foreign suppliers were comparatively not large. As we know well, the United States have spent a large amount of money from federal and state government budget. But the portion of procurement from foreign suppliers is still small, compared with the portion of procurement from domestic suppliers. The main reason are that U.S. has applied for long time the so-called Buy American Act to government procurement positively and maintained many kinds of other domestic regulations which have discriminatory provisions for foreign goods and foreign suppliers. On the recognition of these points, this thesis deals with the Buy American Act and other U.S. domestic laws, regional and bilateral, and plurilateral agreements including WTO Agreement on Government Procurement. As a result, the author found that there are several concerns and problems in the U.S. regulations relating to government procurement. It include the provisions on priority procurement of U.S.-produced products, local contents requirements, set-aside procurement from small business, and exclusion of preferential procurement from the developing countries.