An apparatus and method for allocating a frequency resource to a user equipment (UE) in an orthogonal frequency division multiplexing (OFDM) mobile communication system. A base station receives feedback information including at least mobility information from the UE, and determines from the mobility information whether the UE belongs to a fast group or a slow group. The base station allocates a frequency resource for the UE according to an open-loop solution if the UE belongs to the fast group, allocates a frequency resource for the UE according to a closed-loop solution if the UE belongs to the slow group, and transmits data for the UE using the allocated frequency resource.