PURPOSE: To provide a signal waveform equalizer adjusting method and the signal waveform equalizer capable of adaptively corresponding to a change with the passage of time in a line state by using multilayer perceptron.

CONSTITUTION: The weight values of fixed weights 110a to 110d, 130a to 130c in multilayer perceptron are set up by preceding learning, the weight values are fixed during the operation of the signal waveform equalizer, variable weights 20 are adjusted at the time of preceding learning and during the operation of the signal waveform equalizer at real time, and connection between the weight 20 and a unit 120b and the connection of an output from a weight adjusting circuit 15 are respectively selected by a switch 21. In a preceding learning phase, the learning of all units is executed by a teacher signal to regulate weight values. In a real time phase, the fixed weights are not adjusted and the switching of the switch 21 or the output of an input result of a collation signal to the perceptron is compared with the teacher signal by a weight adjusting circuit 15 to adjust the value of the weight 20.