Abstract: Self-exited vibration may be regard as the most severe and damaging behavior for the mechanism systems. Generally, it is reduced by adding lubricants. In this paper, the non-solution condition in the planar translational joint is investigated under the assumptions that the body is rigid and the clearance in the joint is infinitesimal small. The condition may be regard as one inducement to the self-excited vibration, and it may be applied to every translational joint in the mechanism systems.