A clip includes a pin having at at least a part thereof a noncircular cross-section, and a grommet having an insertion hole into which the pin can be inserted, wherein a part of the grommet is adapted to be expandable by insertion of the pin into the insertion hole. The grommet has slope surfaces provided at an entrance-side hole edge of the insertion hole to lead the pin into the insertion hole when the pin is displaced from a normal position to be in contact with the entrance-side hole edge of the insertion hole.