The purpose of this study was to determine the effect of the pelvic compression belt (PCB) on the electromyography (EMG) activities of trunk muscles during sit-to-stand (SitTS), and stand-to-sit (StandTS) tasks. Twenty healthy subjects (7 men and 13 women) were recruited for this study. The subjects performed SitTS, and StandTS tasks, with and without a PCB. Surface EMG was used to record activity of the internal oblique (IO), external oblique (EO), rectus abdominis (RA), erector spinae (ES), and multifidus (MF) of the dominant limb. EMG activity significantly decreased in the RA (without the PCB, $8.34{pm}6.04$ %maximal voluntary isometric contraction [%MVIC]; with the PCB, $7.64{pm}5.11$ %MVIC), EO (without the PCB, $14.83{pm}11.82$ %MVIC; with the PCB, $11.98{pm}7.60$ %MVIC), MF (without the PCB, $21.74{pm}7.76$ %MVIC; with the PCB, $18.50{pm}8.04$ %MVIC), and ES (without the PCB, $18.39{pm}7.16$ %MVIC; with the PCB, $16.63{pm}6.31$ %MVIC) during the SitTS task and in the IO (without the PCB, $20.58{pm}15.60$ %MVIC; with the PCB, $17.27{pm}12.32$ %MVIlC), RA (without the PCB, $8.04{pm}5.68$ %MVIC; with the PCB, $7.40{pm}4.71$ %MVIC), EO (without the PCB, $13.29{pm}8.80$ %MVIC; with the PCB, $11.24{pm}6.14$ %MVIC), MF (without the PCB, $18.59{pm}7.64$ %MVIC; with the PCB, $15.86{pm}6.48$ %MVIC), and ES (without the PCB, $17.14{pm}6.44$ %MVIC; with the PCB, $15.46{pm}5.62$ %MVIC) during the StandTS task when a PCB was used (p<.05). In men the EMG activity of the MF significantly decreased during the SitTS task when a PCB was used (p<.05): in women, the EMG activity of the RA, EO, MF, and ES during the SitTS task and that of the EO, MF, and ES during the SitTS task significantly decreased when a PCB was used (p<.05). In addition, the rates of change in the EMG activity of each muscle differed significantly during the SitTS and StandTS tasks before and after the use of the PCB. However, the EMG activity did not significantly differ between the male and female subjects. These findings suggest that the PCB may contribute to the modification of activation patterns of the trunk muscles during SitTS, and StandTS tasks.