In steel bridge, fatigue cracks are generally detected by magnetic particle test (MT). MT inspection is ineffective and cost consuming compared with other NDT such as eddy current test (ET). The cost reduction and efficiency of inspection can be achieved if fatigue cracks are detected using ET. It is one of the problems for ET that the accuracy of detection at weld zone decreases due to irregular beads noise. In addition, detection reliability of ET is inferior to MT because in ET inspection, inspector judges existence of flaw from change of eddy current signal in complex plane. In this study, the performance of ET was improved by converting detection signals to C-scope image by using position information.