The present invention relates to a method of transmitting/receiving random access response information in a radio communication system, and a base station and a terminal thereof. According to the invention, in a case where a base station of a radio communication system transmits response information for random access processing requested from terminals, the base station determines whether to transmit non-contention-based response information and contention-based response information for each of one or more terminals, which requests random access, by one radio resource. When determining to be transmitted by one radio resource, the base station transmits the random access response information configured by the non-contention-based response information and the contention-based response information for each of one or more terminals. In addition, when determining to be transmitted by separate radio resources, the base station transmits the random access response information configured by the non-contention-based response information or the contention-based response information for each of one or more terminals. Accordingly, since the response information is efficiently configured from the point of view of allocation and utilization of radio resources, it can support variable and flexible utilization of physical layer radio resources.