To provide a technical means which enables frame members to be connected together without hindrance even in the presence of a misalignment between the axis line of a female screw and that of a male screw, in a frame connecting structure for connecting the frame members together by screwing the male screw, passing through a through-hole of one frame member, into the female screw of a nut-like connecting implement inserted into the other frame member.

The nut-like connecting implement 40 is inserted into the second holes 25 and 26 of an upper frame 20. The diameter D of the second hole 25 or 26 is set larger by 0.50-0.95 mm than the outside diameter d of a bolt-like connecting implement 50. Thus, when the male screw 51 of the connecting implement 50 passes through through-holes 31 and 32 of a vertical frame 30 and the first holes 22 and 23 of the upper frame so as to be screwed into the female screw 41 of the nut-like connecting implement, an automatic aligning action is exerted even in the presence of a misalignment between angles of the axis lines of the male and female screws. In the automatic aligning action, the axis line of the female screw of the nut-like connecting implement is aligned with that of the male screw of the bolt-like connecting implement in such a manner that the nut-like connecting implement is turned in the second holes by an angle equivalent to the misalignment.