We verified that a Cu seed layer could be damaged by a Pt insoluble anode in Cu electrodeposition. When the Cu seed layer was connected to the Pt galvanically, it was pitted and became resistive. The existence of Pt oxides on the Pt developed a potential with respect to the Cu seed layer, and accompanying electron flow from the Cu seed layer to the Pt insoluble anode. This resulted in the dissolution of the Cu seed layer, and the reduction of Pt oxides, which was confirmed by XPS analysis. The pitting current increased with the oxidation time and the surface area of the Pt, indicating the dissolution current on the Cu seed layer was associated with the Pt oxides on the Pt. This study implies that it is necessary to reduce the Pt anode regularly to prevent the Cu seed damage by the Pt anode in Cu electrodeposition.