PURPOSE: To enable the system identifying device which identifies operation parameters of an object system to identify a linear and a nonlinear system and also to make the device into hardware by using a neural network.

CONSTITUTION: This system identifying device is so constituted as to calculate and output an output signal corresponding to an input signal according to a setting changeable data processing function, and is equipped with a data processing means 101 which outputs the identification result of the object system and a setting changing data output means 102 which outputs data for a setting change for changing the data processing function of the data processing means 101 on the basis of the input/output relation of the object system.