A bio-signal processing apparatus, a biometric information detection apparatus, and a method of detecting biometric information are provided. The bio-signal processing apparatus includes a first low pass filter (LPF) configured to have a first cutoff frequency, and output a first preprocessed signal having low frequency components of an input bio-signal that are less than the first cutoff frequency, a second LPF configured to have a second cutoff frequency, and output a second preprocessed signal in which high frequency components greater than or equal to the second cutoff frequency are removed from the input bio-signal, and a processor configured to output an output bio-signal for biometric information detection, based on the output first preprocessed signal and the output second preprocessed signal.