Robot joint device

A robot joint device comprising:

• first and second plates positioned in parallel with each other;
• links each having a first end connected to the first plate and a second end connected to the second plate;
• connecting members configured to connect the two ends of each of the links and the first and second plates, respectively, so that angles and rotations of the links are adjustable relative to the first and second plates;
• a rotary shaft having two ends penetrating the first and second plates and rotatably installed;
• a gear reduction unit installed in the first plate and connected to the first end of the rotary shaft;
• a pulley connected to the second end of the rotary shaft and configured to transmit driving power to the rotary shaft;
• and
• a drive unit configured to transmit the driving power to the pulley,
• wherein the plurality of links is installed such that the plurality of first ends and the plurality of second ends are connected to the first and second plates, respectively, and connection points of the first ends and connection points of the second ends each define a polygon.