The biomechanical analysis of the load carrying effect on different floor surfaces has been conducted. Four different floor surfaces were prepared for ten subjects with each walking at a fixed velocity(1.33 m/sec) while carrying five different loads. The results showed that because of the significant interaction effect between floor slipperiness and the load carrying task, the load carrying effect should be analyzed according to different levels of the floor slipperiness, especially contaminant floors. On oily surfaces, slip distance(SD) and heel velocity (HV) increased whereas stride length(SL) decreased as load increased. In other words, significantly longer SD, faster HV, and no normal gait were found as load increased. As a result, a different protocol should be applied to measure floor slipperiness on oily floors as compared to dry surfaces for tribological approach.