Condition detecting system has a detecting device (1) including a plurality of pieces of distance sensors arranged at one corner of an observing sector such as a toilet, a judging device for judging the condition of a staying person in the observing sector on the basis of the information from the detecting device (1), a signal transmitting section for transmitting the results of judgment, and a warning device for issuing a warning on the basis of the signal from the signal transmitting section, and the plurality of pieces of distance sensors are set to perform detection in a plurality of different directions by using infrared ray beams.