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 therefore difficult to accurately measure a pulse wave and a blood pressure value, and there is a problem of measuring blood pressure stably. It is also difficult to measure blood pressure in daily life activities or to measure blood pressure at predetermined intervals or continuously in a state where a tonometer is always attached. There is consequently a problem of providing a method of holding a biologic information detecting apparatus. The present invention has been achieved to solve the problems and an object of the invention is to provide an easy-to-wear biologic information detecting apparatus for stably detecting biologic information.In order to achieve the above object, biologic information detecting apparatus according to the invention has a structure in which the 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.