To provide a monitor system which uses an existing nurse call system and keeps a record regarding the monitor system utilizing the nurse call system.

The monitor system is constituted of an abnormal sound detection means 7 for detecting the sound in a sickroom, the nurse call system for receiving an abnormal sound detection signal from the abnormal sound detection means 7, a data processing means 6 for receiving the data of detection of the abnormal sound from the nurse call system, a recording means in which the data of detection of the abnormal sound includes information specifying at least an abnormal sound generating source, and the data processing means 6 records associating with a clock, the time of a clock means and abnormal sound detection, and an output means for outputting the content recorded in the recording means.