In a threshold estimation apparatus, a setting unit sets an initial intensity value for each electrode. A selection unit randomly selects an electrode. A stimulation unit, via the selected electrode, stimulates a living subject at an intensity set for the electrode. A detection unit detects the presence or absence of a response evoked by the stimulation. An update unit reduces or increases the intensity associated with the selected electrode, based on the presence or absence of the response evoked by the stimulation. An estimation unit, if the thus updated intensity associated with each electrode satisfies a convergence condition, estimates a convergence value as a threshold associated with the electrode. The threshold estimation apparatus repeats these processes until thresholds associated with all electrodes are estimated. If the same electrode was consecutively selected, the time interval between a stimulation and a subsequent stimulation is adjusted.
