Appropriate measurement and analysis parameters are set according to cerebral function to be measured. To measure gustatory function, a time period of absence of cerebral activity to be measured is set so as not to contain a period of 60 seconds after start of stimulation, an activity period for analysis for an oxyhemoglobin concentration change signal is set so as to contain a period between an instant after a lapse of 16 seconds, and an instant after a lapse of 25 seconds, after the start of the stimulation, and an activity period for analysis for a deoxyhemoglobin concentration change signal is set so as to contain a period between an instant after a lapse of 28 seconds and an instant after a lapse of 37 seconds after the start of the stimulation. Moreover, a time interval between stimulations is set to 80 seconds or more.