A joint structure of a robot for moving an assembly 51 to be connected to a robot link with respect to the robot link, the joint structure includes a first motor 10 for causing the assembly a longitudinal swing motion, a second motor 20 for causing the assembly a lateral swing motion, and a third motor 30 for causing the assembly a rotary motion, wherein the first motor 10 and the second motor 20 are disposed so that the output shaft of the first motor 10 and the output shaft of the second motor 20 are in parallel with each other and are orthogonal to the robot link, and the third motor 30 is disposed so that the output shaft of the third motor 30 is shifted with respect to the central axis of the rotary motion of the assembly 51.