In a robot joint structure, a first main link (42) and a second main link (44) are connected through two movable links including a first movable link (70) and a second movable link (72), and the two movable links are arranged to cross. With this, it becomes possible to increase the overall driven angle of the joint (36) relative to the input, expand the range of motion of the joint in the bending direction, and also raise the critical value of the driven speed (rotational speed).