An apparatus generates a scrambling code in a mobile communication system by performing one or more mask operations on an input state value. The apparatus includes a register memory which receives the state value from an upper layer of the system, a generator which generates an extended state value by performing a mask operation based on initial values of the state value, and a code generator which generates a scrambling code based on at least a first state value which is continuously selected from among the extended state value, a second state value generated based on at least state values (L,R) which correspond to the first state value, and an initial value which has not been used from the initial values.