Plate impact tests were repeated up to three times on carbon steel. The spall damage within the target plate was evaluated with a low frequency scanning acoustic microscope as well as ultrasonic velocity, attenuation (amplitude change of B 2 to B 1 echo) and backscattering intensity. The spall damage generated by the first impact have increased in its density and sizes by the second impact of which stress is higher or lower than the first impact stress. Small cracks once generated have been extended by lower impact stress in successive impacts. The change in B- and C-scan images under repeated impact are well correlated with the change in ultrasonic velocity, attenuation and backs-cattering intensity. These methods give us an advanced means to evaluate nondestructively spall damage and to make clear the mechanisms of the spall damage growth under repeated impacts.