In measurement requiring application of pressure to a tissue of a living body such as blood pressure measurement, noise due to vibration tends to occur. It is difficult to accurately measure a pulse wave and a blood pressure value. It is also difficult to measure blood pressure in life activities or to measure blood pressure at intervals or continuously where a tonometer is always attached. There is consequently a problem of holding a biologic information detecting apparatus. The present invention solves the problems by providing an easy-to-wear biologic information detecting apparatus for stably detecting biologic information. The biologic information detecting apparatus includes a sensor for detecting biologic information in a pair of arms connected via a spindle, and the sensor is tightly attached to a projecting part in a living body, particularly, a tragus of an auricle.