Abstract: A living organism information detection system is capable of appropriately acquiring desired information such as the existence of a living organism, the condition of the living organism, or the like by irradiating a region to be measured with an electromagnetic wave while scanning the region to be measured to thereby cause the transmission/reception of the electromagnetic wave to/from the living organism within the region to be measured to be appropriately performed to thereby accurately detect the temporal change of a phase difference signal. More specifically, an electromagnetic wave transmitting and receiving unit irradiates a region to be measured with an electromagnetic wave that is given strong directivity while scanning the region to be measured, receives a reflected wave, and acquires a phase difference signal corresponding to each position of the region to be measured, and the temporal change of the phase difference signal is detected.