The quantity of waste concrete is one tenth of total waste out of both industry and home in 1997 in Japan. It is about 400, 000, 000 tons a year. The disposal of waste concrete has become a big problem. On the other hand, the lack of natural fine aggregate has also become a serious problem because the requirements to protect the natural environment are increasingly strong. Many engineers at ready-mixed concrete plants are eager to find fine aggregate resources other than river and sea sand. Recycled concrete is expected to be one of the hopeful alternatives. Many researchers have already found it possible to produce a normal strength concrete with the required slump by using recycled aggregate. However, it has been also clear that the durability of concrete with recycled concrete aggregate is sometimes very inferior to that of normal concrete. In this paper, the durability of concrete with recycled concrete aggregate and methods for its improvement are discussed.