A respiratory waveform drawing system (100) for drawing a respiratory waveform of a subject on a bed includes: a plurality of load detectors (11, 12, 13, 14) which are to be placed in the bed (BD) or under legs of the bed, and which are configured to detect a load of the subject； a center of gravity position calculation unit (31) configured to obtain a position of a center of gravity (G) of the subject based on the load of the subject； an oscillation coordinate setting unit (34) configured to perform: obtaining a first extreme point (EP1) at which a distance between an initial origin (TO1) and the position of the center of gravity of the subject shifting from the initial origin is maximized, the position of the center of gravity of the subject at a certain time point being used as the initial origin: obtaining a second extreme point (EP2) which appears at an opposite side of the initial origin from the first extreme point, and at which a distance between the initial origin and the position of the center of gravity of the subject shifting from the first extreme point is maximized: setting a direction connecting the first and second extreme points as a direction of a tentative oscillation axis (TA2): and setting a midpoint between the first and second extreme points as a tentative oscillation origin (T02)； and a waveform drawing unit (35) configured to draw the respiratory waveform by presenting a displacement (D), from the tentative oscillation origin, of a position obtained by projecting the position of the center of gravity of the subject onto the tentative oscillation axis, with respect to time.
