Industrial robot

An industrial robot comprising:

• a lower arm mechanism having a first parallel link structure;
• an upper arm mechanism having a second parallel link structure;
• a base portion forming a lower side part of the first parallel link structure, the base portion being configured to rotate about a vertical axis line;
• a wrist portion forming a distal side part of the second parallel link structure;
• an intermediate connection portion forming an upper side part of the first parallel link structure and a proximal side part of the second parallel link structure, the intermediate connection portion being formed as an integral structure;
• and
• an upper arm biasing unit configured to apply a biasing force against a rotating operation in a direction that the wrist portion descends to an upper arm configuring a lower side part or an upper side part of the second parallel link structure,
• wherein the industrial robot is a four axle robot,
• wherein the wrist portion is configured to rock vertically while always maintaining a vertical axis in a vertical direction when the upper arm is rotated with respect to the intermediate connection portion,
• wherein the upper arm has an arm extension portion that extends from a rotational axis of the upper arm and that exceeds the rotational axis of the upper arm on a proximal end side of the upper arm,
• wherein the upper arm biasing unit is configured so as to apply a biasing force to the arm extension portion,
• wherein the biasing force of the upper arm biasing unit works in a direction that the arm extension portion is pressed in,
• wherein the upper arm biasing unit is positioned rearward with respect to the rotational axis of the upper arm,
• wherein the upper arm biasing unit has a gas spring, and
• wherein the gas spring has a cylinder connected to an intermediate connection portion side and a piston connected to an arm extension portion side.