A method for recording or reproducing data to/from an optical recording medium, through an interface from the optical recording/reading device to a host device, includes receiving a real time write command from the host device if real time data is generated; determining the presence of a defective block listed on a Defect List of a Defect Management Area in a writing area designated by the write command prior to writing the data; returning position information of a defective block to the host device if a defective block is present; and receiving a new write command from the host device to write the data on the optical recording medium based on the returned position information of the defective block.