The IEEE 802.16j standard supports multihop relay function for WiMAX network. The relay technique could enhance the signal strength and help the devices to compete the shadow fading effect from buildings. How to allocate resource becomes an important issue in recent research. In this paper, we discuss the resource allocation with directional antenna in IEEE 802.16j networks. In prior study, the frequency is equally divided according to the number of sectors in a cell. However, the prior allocation schemes often result in waste resource or insufficient bandwidth if the user distribution is not even. The proposed dynamic resource allocation (DRA) scheme considers the user distribution and allocates resource blocks from users'bandwidth request. The simulation results show the improvements from the DRA scheme in terms of utilization of frequency bands and duration of transmission time.