An information playback apparatus includes a first FIR filter, ideal
signal generator, weighted equalization error calculator, and coefficient
calculator. The first FIR filter generates an equalized waveform by
equalizing, to a partial response waveform, a playback data string
obtained by playing back a recorded signal recorded on an information
recording medium. The ideal signal generator generates a target waveform
serving as an equalization target. The weighted equalization error
calculator calculates a data string by performing convolution computation
for an equalization error which is a difference between the equalized
waveform and the target waveform, on the basis of one of the playback
data string and the equalized waveform input from the first FIR filter
and the target waveform input from the ideal signal generator. The
coefficient calculator calculates a tap coefficient for the first FIR
filter on the basis of the data string input from the weighted
equalization error calculator, and outputs the tap coefficient to the
first FIR filter. An information playback method is also disclosed.