A hydraulic ramming apparatus including an apparatus body (14) having a cylinder bore (23) and a guide bore (24) that are successively formed to each other in the apparatus body (14). A piston (30) is slidably inserted into the cylinder bore (23) so as to be reciprocable within the cylinder bore (23). An upper pressure-receiving chamber (31) is defined at an upper end portion side of the piston (30), and a lower pressure-receiving chamber (32) is defined at a lower end portion side of the piston (30). A ramming tool (19), having a rod body (35), can be detachably inserted into the guide bore (24). Also, a mechanism for moving the rod body (35) is provided so as to follow upward movement of the piston (30).