Fly Ash in concrete is known to be effective in improving workability, the reduction of heat of hydration, increasing the long-term compressive strength, and improving durability. Recently, fly ash is consedered an essential material for the high-strength concrete. In this paper, investigations for the strength and workability characteristics was carried out when fly ash was used in the high-strength concrete. As the result, fly ash was effective in increasing the long-term compressive strength, but the short-term compressive strength was gradually decreased with increating fly ash contents. And also the use of superplasticzers was required for providing the proper workability when fly ash contents were increased. The optimum content of fly ash was about 10%.