A biological signal detection device including a first FFT transformer that performs fast Fourier transformation on a signal of a first sensor, and that outputs a complex data row formed by a first real part data row and a first imaginary part data row; a second FFT transformer that performs fast Fourier transformation on a signal of a second sensor, and that outputs a complex data row formed by a second real part data row and a second imaginary part data row; a frequency component subtractor that subtracts the first real part data row from the second real part data row to output a noise-removed first real part data row; and a FFT inverse transformer that performs fast Fourier inverse transformation on the noise-removed first real part data row and the second imaginary part data row.