Patent attributes
A purpose is to prevent a first connection piece string from colliding against a second connection piece string in a robot arm mechanism including a linear extension and retraction joint. In the robot arm mechanism having the linear extension and retraction joint, the linear extension and retraction joint includes an arm section, and an ejection section for supporting the arm section, the arm section includes a first connection piece string 21 made by a plurality of first connection pieces, and a second connection piece string made by a plurality of second connection pieces, the second connection piece string is sent out forward from the ejection section together with the first connection piece string in a state where the second connection piece string is joined to the first connection piece string, and a flexible guide rail for separating the first connection piece string from the second connection piece string and guiding the second connection piece string to the ejection section is interposed between the first connection piece string and the second connection piece string behind the ejection section.