An apparatus and method in which a Base Station (BS) allocates consecutive frequency-domain resources to a Mobile Station (MS) in the multi-carrier system are provided. The method includes sorting all MSs that participate in scheduling for each resource block in a descending order according to priority, selecting an MS including top priority as a best MS among MSs each of which includes top priority for each resource block, allocating a corresponding resource block to the selected best MS, and additionally allocating a corresponding resource block to the best MS if the best MS exists within a window preset in an adjacent resource block located in directions of at least one of decreasing and increasing a resource block index with respect to the allocated resource block, wherein the window includes a specific number of MSs including top priority, where the specific number is based on the window size.