Previously, we have proposed the sampled pattern matching method in order to search for the current distributions in biological systems from local magnetic field measurements. This method is now applied to defect estimation problems in conducting materials. In the present paper, defects are. regarded as equivalent potential sources due to discontinuity of the conductivity at defect positions. The equivalent potentials depend on the externally applied potential source so that this functional relationship between the equivalent and applied potential sources leads to a modified sample pattern matching method named the projective sampled pattern matching method. This new method provides a fairly good result even in the case of multi-defect problems.