This paper presents the results of experimental tests completed to investigate the relationship between earthquake-resistant property and amount of lateral reinforcement of PRC pile. 12 specimens were tested; three with diameter of 600mm and nine with diameter of 300mm. The hollow space of all specemen is filled with, the normal-strength concrete. The specimens that are models of the pile head were subjected to reverse cyclic loading under a constant axial loading. The conclusions of this study are: (1) as the amount of lateral reinforcement increases, the width of shear crack becomes small but the value is influenced by the diameter, (2) the relationship between the deformation capacity and the amount of lateral reinformcement is influenced by the ratio of thickness to diameter and the axial load, (3) the deformation capacity can be evaluated by the section analysis reflecting the concrete confinement provided by the lateral reinforcement.
