For the wireless charging of electric vehicles, metal object detection in the charging area is of great importance to ensure the charging safety and charging efficiency of electric vehicles. Therefore, a novel method is proposed for the metal object detection using the planar coil array. A planar array with 4×4 coils is designed as the main sensing element and images of the conductivity distribution in the charging area are reconstructed using the electromagnetic tomography method. In addition, the contour, location and number of metal objects are obtained by post-processing the reconstructed images. The results from the finite element simulation and experimental investigation prove that the proposed method can effectively detect several kinds of common metal objects.