An electroplating apparatus for a steel pipe, the electroplating apparatus is configured to apply an electroplated coating to a female thread formed on a pipe end portion of the steel pipe, the electroplating apparatus comprising: an inner seal member that is disposed in an interior of the steel pipe, the inner seal member dividing the interior of the steel pipe at a location longitudinally inward of a region on which the female thread is formed; a capsule that is sealingly attached to the pipe end portion, the capsule having a discharge outlet through which a plating solution inside the capsule is discharged, the capsule having an opening that facilitates discharge of the plating solution inside the capsule; an insoluble anode having a cylindrical shape, the insoluble anode being disposed in an inside of the pipe end portion, the insoluble anode passing through the capsule in a sealed relationship to the capsule; and a plating solution supply mechanism that supplies the plating solution to the inside of the pipe end portion sealed by the inner seal member and the capsule, wherein the plating solution supply mechanism includes: a plating solution supply tube that extends along an axis of the insoluble anode, the plating solution supply tube projecting from a leading end of the insoluble anode in the inside of the pipe end portion; and a plurality of nozzles that are attached to a leading end portion of the plating solution supply tube, the nozzles being configured to eject the plating solution between an outer peripheral surface of the insoluble anode and an inner peripheral surface of the pipe end portion, and wherein the insoluble anode has a configuration that does not allow ingress of the plating solution ejected from the nozzles to the insoluble anode. an inner seal member that is disposed in an interior of the steel pipe, the inner seal member dividing the interior of the steel pipe at a location longitudinally inward of a region on which the female thread is formed; a capsule that is sealingly attached to the pipe end portion, the capsule having a discharge outlet through which a plating solution inside the capsule is discharged, the capsule having an opening that facilitates discharge of the plating solution inside the capsule; an insoluble anode having a cylindrical shape, the insoluble anode being disposed in an inside of the pipe end portion, the insoluble anode passing through the capsule in a sealed relationship to the capsule; and a plating solution supply mechanism that supplies the plating solution to the inside of the pipe end portion sealed by the inner seal member and the capsule, wherein the plating solution supply mechanism includes: a plating solution supply tube that extends along an axis of the insoluble anode, the plating solution supply tube projecting from a leading end of the insoluble anode in the inside of the pipe end portion; and a plurality of nozzles that are attached to a leading end portion of the plating solution supply tube, the nozzles being configured to eject the plating solution between an outer peripheral surface of the insoluble anode and an inner peripheral surface of the pipe end portion, and a plating solution supply tube that extends along an axis of the insoluble anode, the plating solution supply tube projecting from a leading end of the insoluble anode in the inside of the pipe end portion; and a plurality of nozzles that are attached to a leading end portion of the plating solution supply tube, the nozzles being configured to eject the plating solution between an outer peripheral surface of the insoluble anode and an inner peripheral surface of the pipe end portion, and wherein the insoluble anode has a configuration that does not allow ingress of the plating solution ejected from the nozzles to the insoluble anode.