[Purpose] The purpose of this study was to investigate the differences in symmetry of sitting posture between typical developmental (TD) children and hemi-cerebral palsy (CP) children. [Subjects and Methods] A school chair mounted on a force platform was used to assess the quiet-sitting pressure distribution of 10 TD and 10 CP children. [Results] The symmetry index of the TD children was significantly closer to zero than that of the CP children irrespective of the latter group’s hemiparetic side. [Conclusions] Sitting posture on school chairs of CP children was more asymmetrical than that of TD children.