Ab initio theoretical calculations have been performed to obtain the stable structures for clusters consisting of a small number of Al atoms. Geometry optimization has revealed that there exists a stable planar structure for Al, clusters. The electron density distributions in the planar structures were examined for the electrically neutral, negative, and positive conditions of the Al clusters. Charge population maps suggested that the outer Al atoms of the cluster play a major role in the storage of extra electrons. In addition to the planar structure, nonplanar structures have been obtained for Al clusters. However, the configuration of these structures is much different from that of Al crystals.