A decoding apparatus adapted for an optical access system comprises an interface, a detection element, and an error correction element. The interface receives a data from an optical storage medium. The detection element executes an error detection on the data received from the interface before the data is buffered to a first memory and generates a defect result in response to the error detection. The error correction element decodes the data in response to the defect result. A decoding method for an optical access system comprising the steps of: receiving a data from an optical storage medium via an interface of the optical access system; executing an error detection on the data received from the interface before the data is buffered to a first memory; generating a defect result in response to the error detection; and decoding the data in response to the defect result.