This paper proposes a system to extract biological signals from aortic pulse waves which are measured by a microphone type pulse wave sensor. Theproposed system enables extraction of three biological signals corresponding to respiratory rate, pulse pressure wave, and RR interval simply by sitting on the seat on which the sensor is laid. Experiment results demonstrated that the mean absolute errors between the signals measured by the proposed system and the conventional sensors are as low as 0.38 times per minute for the respiratory rate, 11.2 mmHg for the pulse pressure wave, and 16.6 ms for the RR interval. The proposed system thus may be applied to monitor the physiological state of a human subject to prevent accident caused by health condition.