To provide a detector for a patient's leaving his or her sickbed that does not make a false alarm even when a patient temporarily leaves his or her sickbed to go to a restroom.

The detector for a patient's leaving his or her sickbed is made up of a first sensor disposed in the vicinity of a sickbed for detecting the presence of an object by a reflected wave of an infrared ray, a second sensor such as a pyroelectric sensor for detecting the presence of the object by a material reflection wave that reflects heat of a human body etc. by infrared irradiation, and a notification part that informs a nurse station that the patient has left his or her sickbed when both the first sensor and the second sensor have stopped detecting the presence of the object. The detector includes a stop button for temporarily stopping the detection operation of the first sensor and the second sensor, a first timer for stopping the detection of the patient's leaving his or her sickbed for a first predetermined time from the time the stop button is operated, and a second timer that starts the detection of the staying in the sickbed of the patient etc. by resuming the detection operation of the first sensor and the second sensor after the elapse of the first timer time, and, when both the first sensor and the second sensor detect the staying in the sickbed of the patient etc. for a second predetermined time continuously, resumes the detection operation for the patient's leaving his or her sickbed.