Abstract: A method of manufacturing a reinforcing bar cage, which is used in a cast-in-place piling method of constructing a reinforced concrete pile for a structure, and an apparatus for manufacturing the same, which allow simple and easy manufacturing of a reinforcing bar cage having an intended cage strength. A hoop is disposed, e.g., spirally with respect to cylindrically arranged main reinforcements, connection between the main reinforcements and the hoop is made by welding crossed portions thereof, and, in connection with the welding, the crossed portions are heated to achieve an intended strength of the reinforcing bar cage.