There are provided a control channel managing apparatus of a base station, a control channel searching apparatus of a user equipment (UE) and a control channel allocating method in a mobile communication system. When an aggregation level is high and a plurality of UEs having the same starting address of a control channel search space are scheduled in a corresponding subframe, control information with respect to conflicting UEs which have lower priorities in terms of allocation of control information can be transmitted through the conflicting UE space. Hence, more control information can be transmitted and the number of available UEs corresponding to the control information increases, and thus an improvement in the performance of the entire network can be achieved.