In this paper, small sized array configurations with small number of element are investigated. As the antenna size, the diameter less than 3λo is assumed. The investigated configurations are a non-uniform arrangement, Triangular arrangement and uniform arrangement. The gain characteristics of these configurations is calculated using the method of moment and compared them. As a result, it is found that optimum number of elements and arrangement to realize the maximum gain is changed by the element and that the triangular arrangement is not necessarily adequate to obtain maximum gain for small sized array antenna with small number of element.