A biological condition determining apparatus for determining a biological condition of a subject on a bed, the apparatus comprising: a plurality of load detectors (11, 12, 13, 14) which are placed in the bed or under feet of the bed and which are configured to detect a load of the subject; a respiration information extracting unit configured to extract a respiration information signal (BS1; BS2; BS3; BS4) from the output signal (S1; S2; S3; S4) of each load detector; a determining unit configured to determine a respiratory condition of the subject by comparing one of the extracted respiration information signals with referential information prepared and stored beforehand; and an output unit (5; 6) configured to output the respiratory condition of the subject determined by the determining unit, wherein each extracted respiration information signal is a detected respiration waveform showing temporal variation; characterized in that the referential information comprises a plurality of referential waveforms, each referential waveform denoting one type of respiratory condition; and further characterized in that the comparing by the determining unit comprises: (a) comparing the detected respiration waveform having the largest amplitude among the plurality of detected respiration waveforms with one of the stored referential waveforms, and (b) in a case that the detected respiration waveform having the largest amplitude matches or resembles the one referential waveform, determining that the respiratory condition of the subject is the respiratory condition denoted by the one referential waveform matching or resembling the detected respiration waveform having the largest amplitude, and (c) in a case that the detected respiration waveform having the largest amplitude does not match or does not resemble the one referential waveform, comparing the detected respiration waveform having the largest amplitude with another one of the stored referential waveforms, and (d) if needed, repeating steps (b) and (c) to determine a respiratory condition of the subject. a plurality of load detectors (11, 12, 13, 14) which are placed in the bed or under feet of the bed and which are configured to detect a load of the subject; a respiration information extracting unit configured to extract a respiration information signal (BS1; BS2; BS3; BS4) from the output signal (S1; S2; S3; S4) of each load detector; a determining unit configured to determine a respiratory condition of the subject by comparing one of the extracted respiration information signals with referential information prepared and stored beforehand; and an output unit (5; 6) configured to output the respiratory condition of the subject determined by the determining unit, wherein each extracted respiration information signal is a detected respiration waveform showing temporal variation; characterized in that the referential information comprises a plurality of referential waveforms, each referential waveform denoting one type of respiratory condition; and further characterized in that the comparing by the determining unit comprises: (a) comparing the detected respiration waveform having the largest amplitude among the plurality of detected respiration waveforms with one of the stored referential waveforms, and (b) in a case that the detected respiration waveform having the largest amplitude matches or resembles the one referential waveform, determining that the respiratory condition of the subject is the respiratory condition denoted by the one referential waveform matching or resembling the detected respiration waveform having the largest amplitude, and (c) in a case that the detected respiration waveform having the largest amplitude does not match or does not resemble the one referential waveform, comparing the detected respiration waveform having the largest amplitude with another one of the stored referential waveforms, and (d) if needed, repeating steps (b) and (c) to determine a respiratory condition of the subject. (a) comparing the detected respiration waveform having the largest amplitude among the plurality of detected respiration waveforms with one of the stored referential waveforms, and (b) in a case that the detected respiration waveform having the largest amplitude matches or resembles the one referential waveform, determining that the respiratory condition of the subject is the respiratory condition denoted by the one referential waveform matching or resembling the detected respiration waveform having the largest amplitude, and (c) in a case that the detected respiration waveform having the largest amplitude does not match or does not resemble the one referential waveform, comparing the detected respiration waveform having the largest amplitude with another one of the stored referential waveforms, and (d) if needed, repeating steps (b) and (c) to determine a respiratory condition of the subject.