PURPOSE: To perform optimum equalization in a short time by a memory with small capacity by storing the memory with tap coefficients for necessary transmission characteristics, and performing convolutional arithmetic of each tap coefficient for a combination of plural transmission characteristics.

CONSTITUTION: The memory 205 is stored with tap coefficients for respective single characteristics of the amount of delay of a parabolic group, the amount of delay of a linear group, the amount of linear amplitude, and the amount of parabolic amplitude. When a specifying signal for the amount of equalization of a characteristic to be equalized individually is inputted from a specifying terminal 201 for the amount of delay of the parabolic group, specifying terminal 202 for the amount of delay of the linear group, specifying terminal 203 for the amount of linear amplitude, or specifying terminal 204 for the amount of parabolic amplitude, the tap coefficient corresponding to specified data is read out of the memory 205 and supplied to a terminal 207 as it is. When ≥2 kinds of characteristics are specified, an arithmetic circuit 206 performs convolutional arithmetic for respective characteristics read out of the memory 205, and calculates and supplies a new tap coefficient to the terminal 207.