In this investigation, the effect of step length, walking speed and subject on traction coefficient between a shoe sole and floor was clarified and desirable walking conditions for reducing the chance of slipping were also suggested. From the gait experiments, a walk with shorter step length and higher walking speed is effective to reduce the chance of slipping irrespective of subjects. Based on a kinematic analysis of COM and COP during walking, the peak value of traction coefficient at heel-strike period |F h/F n| h or that at toe-off period |F h/F n| t on dry walkway increases with an increase of tan|θ h| or tan|θ t|. θ h or θ t is an angle between vertical line through COM and the line connecting COM and COP at the moment when traction coefficient takes peak value at heel-strike or toe-off period. These results indicate that a walk with smaller θ h and θ t is effective for prevention of slip during walking.