The author considers Husimi-Temperley model of the imperfect gas, whose each particle interacts with all other particles. It is shown in this model that the analytic singular point zs of Mayer series by cluster integrals is not the condensation point, and that the isotherm obtained from the canonical partition function has a metastable part, while that from the grand partition function has a horizontal part. It is also shown that this model does not go beyond the scheme of the theories of Mayer, Yang-Lee, and Ikeda. Some remarks in the general case are discussed in connection with this model.