To reduce the weight of a pile holding cylinder to hold a steel pipe pile, and to actualize efficient low-head pile driving work by forming only one engaging protrusion of the steel pipe pile to reduce manhours for welding work.

This pile driver comprises: an upper pile engaging cylinder 25 and a lower pile engaging cylinder 26 mounted at both ends of an output cylinder 22 of a rotation driving device 19; and a guide pipe 27 arranged in the output cylinder 22 for connecting the upper and lower pile engaging cylinders together. The guide pipe 27 has a sufficient inner diameter for a steel pipe pile 23 to be inserted therethrough. The pile engaging cylinders 25 and 26 comprise: cylinder bodies 25a and 26a corresponding to the outer diameter of the steel pipe pile 23; flange parts 25b and 26b provided on the cylinder bodies and anchored to the ends of the output cylinder 22; recessed grooves 25f and 26f provided in the inner peripheral faces of the cylinder bodies for an engaging protrusion 23a of the steel pipe pile to pass therethrough; engaging protrusion engaging parts 25g and 26g provided at the axial intermediates of the recessed grooves while neighboring the recessed grooves in their peripheral directions; and fitting cylinder parts 25d and 26d protruded on the output cylinder internal sides of the pile engaging cylinders for the opening ends of the guide pipe 27 to be fitted thereto, respectively.