The invention provides a sound source separation system, a sound source separation method, and an acoustic signal acquisition device which can precisely separate a target sound and a disturbance sound coming from an arbitrary direction, and which ensures miniaturization of a device. A sound source separation system 10 comprises two microphones 21, 22 disposed side by side in a direction in which a target sound comes from, a target sound superior signal generator 30 which performs a linear combination process for emphasizing the target sound, using the received sound signals of the microphones to generate a target sound superior signal, a target sound inferior signal generator 40 which performs a linear combination process for suppressing the target sound, using the received sound signals of the microphones 21, 22, to generate a target sound inferior signal, and a separation unit 60 which separates the target sound and a disturbance sound, using a target sound superior signal spectrum and a target sound inferior signal spectrum.