PURPOSE: To realize a mechanism deciding a synapse weight equivalent to a living body by detecting the change of voltage or current at an information output side caused by the ion concentration change of an information transmission ion.

CONSTITUTION: An exciting material TE according to the intensity of an exciting stimulus is supplied to an exciting ion channel 4a in an information input side room 2a. A suppressing material TI according to the intensity of suppressing stimulus is supplied to a suppressing ion channel 4b in an information input side room 2b. Thus, an exciting ion channel activating protein E and a suppressing ion channel activating protein I liberating the exciting ion channel 4a or the suppressing ion channel 4b together with the exciting material or suppressing material are produced. An information output means 10 detects the change of the sodium ion concentration in an information output side room 3 as voltage by taking the sodium ion concentration in the information input rooms 2a and 2b as reference to output it.