A planetary gear reduction device for a super high speed reduction, the planetary gear reduction device comprising: a planetary gear reduction unit providing a primary reduced speed obtained by primarily reducing a rotational speed of a motor which is connected to the planetary gear reduction unit; and an inscribed planetary gear reducer having an input shaft module, which has an end portion connected to the planetary gear reduction unit and is formed by coupling at least two separate parts with each other forming one body, and an output shaft module for outputting a secondary reduced speed by further reducing the primary reduced speed by an interaction with the input shaft module, characterized by that the input shaft module of the inscribed planetary gear reducer comprises: a first input shaft module having one end portion disposed at a side of the output shaft module; and a second input shaft module having one side coupled to the first input shaft module and another side connected to the planetary gear reduction unit, wherein the first input shaft module comprises: a first module head disposed at the side of the output shaft module and having an outer surface to which an input gear is connected; and a first module shaft connected to a second module head, wherein the second input shaft module comprises: a second module hollow body having an empty hollow shape and into which the first module shaft is inserted; and a second module flange formed on an end portion of the second module hollow body to be greater than a diameter of the second module hollow body. a planetary gear reduction unit providing a primary reduced speed obtained by primarily reducing a rotational speed of a motor which is connected to the planetary gear reduction unit; and an inscribed planetary gear reducer having an input shaft module, which has an end portion connected to the planetary gear reduction unit and is formed by coupling at least two separate parts with each other forming one body, and an output shaft module for outputting a secondary reduced speed by further reducing the primary reduced speed by an interaction with the input shaft module, characterized by that the input shaft module of the inscribed planetary gear reducer comprises: a first input shaft module having one end portion disposed at a side of the output shaft module; and a second input shaft module having one side coupled to the first input shaft module and another side connected to the planetary gear reduction unit, wherein the first input shaft module comprises: a first module head disposed at the side of the output shaft module and having an outer surface to which an input gear is connected; and a first module shaft connected to a second module head, wherein the second input shaft module comprises: a second module hollow body having an empty hollow shape and into which the first module shaft is inserted; and a second module flange formed on an end portion of the second module hollow body to be greater than a diameter of the second module hollow body. a first input shaft module having one end portion disposed at a side of the output shaft module; and a second input shaft module having one side coupled to the first input shaft module and another side connected to the planetary gear reduction unit, wherein the first input shaft module comprises: a first module head disposed at the side of the output shaft module and having an outer surface to which an input gear is connected; and a first module shaft connected to a second module head, wherein the second input shaft module comprises: a second module hollow body having an empty hollow shape and into which the first module shaft is inserted; and a second module flange formed on an end portion of the second module hollow body to be greater than a diameter of the second module hollow body. a first module head disposed at the side of the output shaft module and having an outer surface to which an input gear is connected; and a first module shaft connected to a second module head, wherein the second input shaft module comprises: a second module hollow body having an empty hollow shape and into which the first module shaft is inserted; and a second module flange formed on an end portion of the second module hollow body to be greater than a diameter of the second module hollow body. a second module hollow body having an empty hollow shape and into which the first module shaft is inserted; and a second module flange formed on an end portion of the second module hollow body to be greater than a diameter of the second module hollow body.