Abstract: Conventionally, when a biological information collecting device is used for measurement, an electrode is directly attached to a human body, accurate information cannot be collected and measurement through a lead wire is performed, for long time constraining the human body because of the lead wire. A device proposed to solve the problem comprises a capacitive sensor used for detecting a signal from the human body, and therefore the temperature characteristics are not good, bringing out a drawback that the signal varies in a low-frequency range. A biological information collecting device according to the invention comprises a closed pneumatic sound sensor having a gas-tight air bag made of soft rubber, plastic, or cloth or a cabinet made of metal, rubber, plastic, or wood. Biological information about the respiration, the cardiac rate (cardiac cycle), and the body movement due to, e.g.