A method for generating error detection code is disclosed. Firstly, a first error detection code PEDC is derived by using 12-byte unknown sector data information including ID, IED, RSV and the 2048-byte main data while the main data is delivered from a host. Secondly, a second error detection code MEDC is obtained by using known 12-byte sector data information including ID, IED, RSV and the 2048-byte main data. Thereafter, the real error detection code EDC is obtained by applying an exclusive-OR operation to both the PEDC and MEDC.