A linear extension and retraction mechanism has a plurality of flat-plate shaped first connection pieces and a plurality of grooved-frame shaped second connection pieces. Each of the first connection pieces is bendably connected at front and rear end surfaces to adjacent first connection pieces. Each of the second connection pieces is bendably connected at bottom front and rear end surfaces to adjacent second connection pieces. The first and second connection pieces become linearly rigid when overlapped together, and the first and second connection pieces return to a bent state when separated from each other. A cushion member is mounted on the front end surface of each first connection piece to cushion a shock of a collision between end surfaces of the first connection pieces. A slot section for fitting the cushion member is provided in the front end surface of each first connection piece.