Annular mode in the extratropical atmosphere, whether it is dynamically reasonable concept, is examined in the so--called aquaplanet general circulation model. Standard analyses of the empirical orthogonal function (EOF) and one--point correlation to the low--frequency surface pressure anomaly yield results similar to previous studies: the dominant annular mode in EOF but more non--annular distribution in the correlation maps, leading to a difficulty to argue whether the annular structure is a statistical artifact. Similar analyses to the upper--tropospheric streamfunction are, however, able to successfully distinguish the annular mode from a slowly propagating, wavenumber-five (m = 5) disturbance, both of which are forced by high--frequency eddies. Since the amplitude of the m = 5 waves is weakly interrelated to the annular mode, snapshots of the annular mode extreme tend to accompany large non--annular components. In the aquaplanet experiment with zonally varying boundary condition involved, the annular mode in streamfunction becomes more prevailing, in which the low--frequency eddy itself, in addition to the high--frequency eddies, drives the zonal--mean wind anomaly.