A line laying structure for a wrist of a robot capable of enhancing durability of lines of cables/pipes for flowing electricity, air, water, etc. to an end effector attached to the wrist, and reducing a restriction of angle of rotation of a wrist axis by rotation of the other wrist axes. First, second and third wrist elements of the wrist are rotatable around fist, second and third axes, respectively. The first wrist element is fixed to a distal end of a forearm of the robot, to be rotated on a mounting base with the forearm as a unit. The lines are clamped on the mounting base by a line retainer and laid inside the forearm and clamped at a distal end of the forearm inside and outside thereof by line retainers. The lines are then clamped by line retainers provided on the second wrist element and introduced to the third wrist element. Then, the lines are clamped by the line retainer provided on the third wrist element and drawn outside thereof to be connected with the end effector. Only limited sections S1 S3 of the lines between the line retainers are subjected to bending, twisting and translation by the rotation of the wrist elements and the other sections of the lines are not influence by the rotation of the wrist elements, to enhance durability of the lines.