A bed monitoring system for monitoring a subject on a bed, the system comprising: a plurality of load detectors which are to be placed in the bed or under legs of the bed and which are configured to detect a load of the subject; a center of gravity position calculating unit configured to obtain a temporal variation of a center of gravity position of the subject based on the detected load of the subject; a body motion information determining unit configured to obtain a body motion information based on the obtained temporal variation of the center of gravity position of the subject, the body motion information being an information on a movement of a whole or a part of the whole body of the subject different from a movement caused by a respiration of the subject; a respiratory rate calculating unit configured to calculate a respiratory rate of the subject based on the obtained temporal variation of the center of gravity position of the subject and the body motion information obtained by the body motion information determining unit; characterised in that the system further comprises: a subject information detecting unit configured to detect at least one of an image information of the subject, and a temperature information of the subject; and a condition determining unit configured to determine contents of a body motion of the subject by using both of the body motion information of the subject, and the image information of the subject or the temperature information of the subject, wherein the condition determining unit is configured to determine the contents of the body motion of the subject based only on the image information of the subject or the temperature information of the subject in a case that the contents of the body motion of the subject cannot be determined based on the body motion information of the subject. a plurality of load detectors which are to be placed in the bed or under legs of the bed and which are configured to detect a load of the subject; a center of gravity position calculating unit configured to obtain a temporal variation of a center of gravity position of the subject based on the detected load of the subject; a body motion information determining unit configured to obtain a body motion information based on the obtained temporal variation of the center of gravity position of the subject, the body motion information being an information on a movement of a whole or a part of the whole body of the subject different from a movement caused by a respiration of the subject; a respiratory rate calculating unit configured to calculate a respiratory rate of the subject based on the obtained temporal variation of the center of gravity position of the subject and the body motion information obtained by the body motion information determining unit; characterised in that the system further comprises: a subject information detecting unit configured to detect at least one of an image information of the subject, and a temperature information of the subject; and a condition determining unit configured to determine contents of a body motion of the subject by using both of the body motion information of the subject, and the image information of the subject or the temperature information of the subject, wherein the condition determining unit is configured to determine the contents of the body motion of the subject based only on the image information of the subject or the temperature information of the subject in a case that the contents of the body motion of the subject cannot be determined based on the body motion information of the subject. a subject information detecting unit configured to detect at least one of an image information of the subject, and a temperature information of the subject; and a condition determining unit configured to determine contents of a body motion of the subject by using both of the body motion information of the subject, and the image information of the subject or the temperature information of the subject, wherein the condition determining unit is configured to determine the contents of the body motion of the subject based only on the image information of the subject or the temperature information of the subject in a case that the contents of the body motion of the subject cannot be determined based on the body motion information of the subject.