A new inversion technique to locate buried pipes has been developed. The inversion algorithm estimates the location by searching the minimum prediction error for the first arrival time. Thus, the technique is a kind of parameter optimization techniques and does not image anything, but it can indicate the location obviously. The comparison of the predictions with measurements is performed focusing on the arrival curve shape unlike conventional ray tomography. Thus, the arrival time picking does not affect the estimation, and the arrival curve can easily be selected by maximum amplitudes or thresholding, for instance. The technique can explicitly and efficiently use a priori information on the target in the forward modeling. Therefore, the inversion calculation can be done very quickly and is stable. The inversion technique is verified with field data for a metallic pipe. The inversion result can estimate the location successfully. Therefore, the inversion technique is suitable for this purpose and to use on site. It can provide useful information also to non-specialists of radar and geological technologies who are involved with civil engineering.