DUMMY PLUG AND DUMMY PLUG STRUCTURE

The present invention provides a dummy plug that can be automatically corrected to a normal orientation, and a dummy plug structure. A dummy plug (10) is provided with a square fitting part (12) extending in the longitudinal direction. The square fitting part (12) has four corner sections (15) at diagonal positions about the axis in the longitudinal direction. Each of the four corner sections (15) has a chamfered section (17) outwardly expanding rearward and having a rearwardly tapering width dimension in the direction about the axis. Each chamfered section (17) has a ridgeline section (18) extending in the longitudinal direction and protruding outward. Each ridgeline section (18) is inclined so as to be offset further in one direction about the axis as the ridgeline section (18) extends rearward.