In a system having an interface utilizing electroencephalograms, a users burden of calibration for accurately measuring electroencephalograms is eliminated, and it becomes possible to maintain a high distinction accuracy of electroencephalograms.An electroencephalogram interface (IF) system 1 includes an electroencephalogram IF section (13) for distinguishing a request of a user based on electroencephalograms, and identifies a function which is in accordance with the request. An electroencephalogram distinction method adjustment apparatus (2, 50) includes: an analysis section (14, 52) for detecting a change in a characteristic quantity of a stimulation given to the user, thus detecting a change in the stimulation a storage section (15) for storing a waveform of an event-related potential during a period after a point in time when the change in the stimulation is detected an extraction section (16) for extracting a characteristic quantity of the user based on the stored waveform and an adjustment section (17) for, based on the extracted characteristic quantity, adjusting in the electroencephalogram IF section (13) a distinction method for a request based on an electroencephalogram signal.
