A model for predicting trajectory of flame/plume ejected from a fire compartment was formulated incorporating the effect of wall above the opening. As observed in the reduced scale experiment, which was reported in the previous paper, window flames/plumes were divided into following categories with regard to trajectory configuration: window flames/plumes which rise almost vertically after ejection maintaining certain separation from the wall; window flames/plumes which rise upward after ejection and attach to the wall in the downstream. In the model, these trajectories were approximated with cubic polynomials respectively, and their coefficients were expressed as functions of a dimensionless parameter F. The parameter F was derived from the conservation equation of momentum, which incorporates the effect of pressure gradient across the current Critical condition for the occurrence of flow attachment was described as a proportion of maximum separation length versus opening width. Trajectories predicted by the proposed model were then compared with the measurement data, and reasonable agreements were obtained.