In a state in which a fuel pipe (11) and a connector (13) are already joined, a swing fulcrum portion (14h) of a drop-off prevention holder (14) is engaged with the fuel pipe (11), and making the drop-off prevention holder (14) swing with this portion as a fulcrum allows a U-shaped first cutout (14d) formed in a first face (14b) to be fitted onto a small diameter portion (13c) of the connector (13), thus restricting the distance between a step (13b) and a second flange (11b) and thereby restraining the fuel pipe (11) and the connector (13) so that they do not separate. Since it is necessary to carry out a snap fitting operation only once in order for the small diameter portion (13c) of the connector (13) to pass through a narrow throat portion (b) formed partway along the first cutout (14d) of the drop-off prevention holder (14), the operation becomes easy compared with a case where snap-fitting operations are required a plurality of times, and the drop-off prevention holder (14) can be installed easily.