In this paper, a simple and robust method of unstructured dynamic mesh with surface mesh movement method for unstructured triangle/tetrahedral meshes is proposed. The method is developed to avoid the generation of squashed invalid elements by considering each elemental shape. With several three-dimensional applications, it is demonstrated that the present method significantly improves robustness for problems concerning large body motion without much penalty in CPU time. The use of the present method for mesh movements on curved surfaces is also discussed. Its capability is demonstrated for the surface mesh movement in the tail-fuselage juncture region of an airplane.