To arrange two types of fuel inlets in a recess of an adaptor without increasing the area of a fuel lid as compared with before.

The adaptor 20 comprises a first adaptor 30 and a second adaptor 32 which are manufactured independently, and integrally assembled. When the adaptor is viewed from the side, an inclination angle of an outer circumference 30a of the first adaptor 30 and an inclination angle of an outer circumference 32a of the second adaptor 32 is different by an angle θ. The second opening area S2 in a connection part 38 where the first adaptor 30 and the second adaptor 32 are connected in a vertical cross-sectional surface is set to be larger than the first opening area S1 in an opening 16 of a recess 18 (S1<S2).