Disclosed is an acoustic sensor including a semiconductor chip comprising two or more transistors. At least two of the transistors are each connected to a piezoelectric thin film, and the piezoelectric thin film is directly or indirectly disposed over a semiconductor substrate such that a conduction state of each of the at least two transistors varies in response to a pressure of sound waves incident on the piezoelectric thin film, and the two or more transistors are connected to constitute a single amplifier circuit so as to add up and amplify a signal with a strength in response to the conduction state of each of the at least two transistors, and output the amplified signals.
