When allocating CCEs as a radio resource to a new radio terminal within a predetermined sector, the disclosed radio base station (1) acquires the new AL corresponding to the new radio terminal, and identifies CCEs that cannot be allocated (non-allocatable CCEs) determined in response to an AL that is larger than said new AL. Furthermore, when a new search space wherein the CCE is completely unused exists among new search spaces corresponding to the new radio terminal, and when a non-allocatable CCE is contained in said new search space wherein the CCE is completely unused, the radio base station (1) allocates said non-allocatable CCE to the new radio terminal.