PURPOSE: To provide a pressure force detection apparatus which can detect a pressure force surely even when an external noise exists.

CONSTITUTION: A pressure force detection apparatus 4 is provided with a tubular sensor 10 which is crushed by a pressure force and which cuts off sound waves propagated at the inside and with a microphone 14 which receives the sound waves. In the pressure-force detection apparatus, a microphone 15 which receives a noise generated at the inside and which outputs a signal corresponding to the noise and a differential amplifier 33 which subtracts the signal output by the microphone 15 from a signal output by the microphone 14 are installed. The component of the noise is cancelled from the output signal of the microphone 14, and only an electric signal corresponding to the component of the sound waves propagated at the inside of the sensor 10 is taken out.