A respiratory waveform drawing system (100) for drawing respiratory waveforms of subjects (S) on a bed (BD) includes: a plurality of load detectors (11, 12, 13, 14) which are to be placed in the bed or under legs of the bed, and each of which is configured to detect loads of the subjects and output the detected loads of the subjects as a load signal； a subject number determination unit (3) configured to determine a number of the subjects on the bed based on a frequency spectrum of the load signal； a waveform separation unit (33) configured to separate a load component of each of the subjects from the load signal outputted from each of the plurality of load detectors, in a case that the number of the subjects on the bed is determined to be more than one； a center of gravity position calculation unit (31) configured to calculate a position of a center of gravity of each of the subjects based on the separated load component of each of the subjects； and a waveform drawing unit (35) configured to draw a respiratory waveform of each of the subjects based on a temporal variation of the position of the center of gravity of each of the subjects.
