An extension/retraction device includes a cylindrical stationary leg section having a base at the upper end thereof, a cylindrical movable leg section in which the stationary leg section is fitted so as to be slidable in the longitudinal direction, an engagement tube having an upper end formed in a stepped shape and installed in the stationary leg section so as to be coaxial with the movable leg section and so as to be pivotable about the cylinder axis of the movable leg section, a pressing spring installed within both the movable leg section and the stationary leg section, a pulling spring held within the pressing spring, a guide tube having an upper end affixed to the base and installed in the engagement tube, an engagement section fitted to the lower end of the engagement tube, and a spacer installed between the lower end of the guide tube and the engagement tube.