Coupling structure and parallel link robot

A coupling structure comprising:

• a pair of attachment members that are supported on two links that each have a longitudinal axis and move parallel to each other with a gap therebetween so as to be able to rotate about rotation axes that are perpendicular to a plane that includes the longitudinal axes of both of the links;
• and
• a coupling mechanism that fixes a distance between the pair of attachment members in an adjustable manner;
• wherein the coupling mechanism comprises two male screws fixed to respective attachment members and a nut member having two female screws that respectively engage with the two male screws, the two male screws are disposed on a same axis and are in a reverse thread relationship;
• wherein two fixing nuts are respectively fastened to the male screws, wherein, when the distance between the attachment members is adjusted by the respective male screws and the respective female screws, the two fixing nuts are fastened so as to be in firm contact with the nut member;
• and
• wherein each of the fixing nuts comprises an outer circumferential wall that surrounds, on an opposite side of the nut member, the male screw fastened to the fixing nut.