PURPOSE: To lock a locking pawl easily and properly in a through hole and improve stability and waterproofness of a grommet function in a grommet for a wire harness comprising a grommet main part and a hard fitting member for combining and coupling the harness with the main part.

CONSTITUTION: A rotational coupling mechanism is provided in such a way that a fitting member 3 is divided into an upper fitting member 11 comprising a coupling plate 13 to be coupled with a grommet main part 2 and a lower fitting member 12 comprising a base plate 14 having a locking pawl 5 downward so that it may comprise a cross sectional L shaped female hook piece 16 and a male hook piece 17 engaging with each other as a mutual pair mounted on the lower side of the coupling plate 13 and a top side of the base plate 14 respectively. A grommet main part 2 through which the wire harness 10 is inserted is joined to the lower fitting body 23 previously cocked to the through hole 8 by coupling the upper fitting member 11 downward and the female nd male hook pieces 16 and 17 are engaged and coupled together by turning them a little and fitted to the through hole 8.