Eddy current testing (ECT) using sinusoidal excitation is practical in various fields and its electromagnetic phenomena is becoming clear by using numerical analysis. On the other hand, some problems are remained in ECT technology: for example, high-sensitivity detection, testing for magnetic material, thick structure. In this paper, in order to obtain guidelines for the design of ECT probes, eddy current distribution induced by exciting coil was reconsidered. Furthermore, we tried to improve the distribution by the combination of more than one exciting coil in order to high-sensitivity detection