Abstract: An FEM simulation using three-dimensional beam element was performed in order to study the causes of cracking on the top of curved prestressed concrete girder bridge piers, where the prestressing tendons were simplified as forces acting on the concrete girder. The results indicate that the direction of moment on the top of a single pillar pier caused by prestressing and that caused by dead load are identical, and the former is 1 order of magnitude higher. These two moments are the main causes of cracking on the top of the piers. By comparative computation, applicable suggestions were proposed to prevent the cracking of a pier.