Internal planetary reduction gear

An internal planetary reduction gear comprising:

• an internal-gear integrated main body having an internal gear integrally formed on an inner wall thereof, and on which a plurality of components for speed reduction are mounted, the plurality of components comprising;
• an input shaft module formed as a single body by coupling at least two separated parts with each other, having an input gear formed on an end portion thereof, and connected to the internal-gear integrated main body;
• and
• an output shaft module connected to the input shaft module to interact therewith and reducing and outputting a speed of the rotary power of the motor that is input from the input shaft module,
• wherein the input shaft module comprises:
• a first input shaft module having one end portion arranged at a side of the output shaft module, and
• a second input shaft module connected to the motor and coupled to the first input shaft module,
• wherein the first input shaft module comprises:
• a first module head arranged at the side of the output shaft module and having an outer surface to which the input gear is connected;
• and
• a first module shaft connected to the first module head and inserted into the second input shaft module.