We examine a simple approximation to the one-loop Higgs potential in the supersymmetric standard model. We study the conditions under which our approximation can well simulate the full one-loop results. The results by our method are compared with those by the full one-loop potential as well as the tree one in several examples. It turns out that our method works quite well in many cases and thus provides a useful calculating method, instead of a complicated evaluation of one-loop potential.