In recent studies, it has been recognized that concrete deterioration is accelerated by growth of the fine cracks of a few micron meter wide which was induced by dry shrinkage and/or freezing damage. Research of the concrete which carries out self- healing of these fine cracks has been abundantly expected. To confirm the ability of fly ash on self-healing, we conducted fundamental test of mortar using fly ash (replacement ratio: 20%) which was deteriorated by accelerated freeze-thaw cycle until the relative dynamic modulus of elasticity reduced to 80% and 60%. The mortar specimens were then cured in water at 40°C and 20°C. We have evaluated the self- healing degree of the cured mortar specimens by strength test, some durability tests, and concrete structure observations. From the test results, it was confirmed that fly ash functioned effectively as a self-healing material of concrete.