PURPOSE: To adjust an output value based on a sigmoid function to a unit computing element of the post-stage and to exactly binarize it by changing a weight coefficient applied to an input value and a gain for determining an output value by an operation of a prescribed number of times.

CONSTITUTION: The unit computing element is provided with an input value arithmetic means 1, an output arithmetic means 2, a gain changing means 3, an error arithmetic means, and a weight coefficient updating storage means 5. In this state, with respect to input values xi1.j - xin.j of the intermediate layer unit computing element an output value xj of the output value arithmetic means being an output value of the intermediate layer unit computing element is calculated as a sigmoid function value corresponding to the product of a value Xj obtained by multiplying its input values xi1.j - xin.j by each weight coefficient Wi1.j - Win.j and a gain gj changed in accordance with a prescribed number of times of the operation, and also, each weight coefficient Wi1. - Win.j is updated at every operation, based on each gain gj, the output value xj and an error output δj determined in accordance with a backward error from the unit computing element of the post-stage. In such a way, the output value xj can be binarized exactly.