The present invention provides a brain-computer interface device. The brain-computer interface device may include: a preprocessor for preprocessing a readiness potential signal measured by a brain wave detection device； a noise eliminator for eliminating noise from the preprocessed readiness potential signal； a signal processor for extracting features related to a user's intention by calculating at least one of the intensity of the readiness potential signal from which noise is eliminated, the phase of the readiness potential signal, the place where the readiness potential signal is generated, and the time when the readiness potential signal is generated； and a data classifier for classifying the extracted features to determine the user's intention.
