The purpose of this study was to clarify the characteristics of postural control in persons with amputation and to examine the influence of two socket types. A group of six men with unilateral trans-femoral amputation (amputation group, AG) participated in this study. A group of twenty healthy men (control group, CG), matched for age, were also tested. The subjects performed two tests as follows: (1)quiet upright standing task (single-task, ST) and (2)upright standing and concurrent attention-demanding task (calculation task) (dual-task, DT). The center of pressure (CP) was measured using a force platform during the two conditions. In addition, the trajectory length (LNG), the rectilinear area (REA), and the lateral and fore-aft direction were calculated. Significant differences were observed between AG and CG concerning LNG and REA in ST (p<.05). But the effect of a cognitive task on the efficiency of postural control was not shown in either group. In contrast with CG, CP in AG showed a movement to the non-amputation side in the lateral direction (p<.05). Further, CP was moved to the non-amputation side as an effect of the cognitive task (p<.05). In regard to the effect by socket type, there was a tendency for LNG and REA in the quadrilateral socket to be smaller than in the ischial-ramal containment socket.