Random scattering of sensors may cause some location not to be covered. In such a case, it is useful to make use of mobile sensors that can move to eliminate the coverage holes. Wang et al [1]. proposed self-deployment schemes of mobile sensors by using Voronoi polygon. However, some coverage holes still remain after the execution of the schemes. We propose a new self-deployment scheme using the centroid (geometric center) of each sensor's Voronoi polygon as the moving target position. The performance evaluation shows that the proposed scheme achieves better results than the existing schemes in terms of fast coverage expansion.