A fuel device FS includes a discriminating portion 50, an operation member, an abutting member 57 and an open/close member 70. The discriminating portion 50 includes an discrimination opening GL formed of a first portion and a second portion. The first portion is an opening corresponding to an external diameter of a small-diameter nozzle FNS. The second portion is an opening having a shape corresponding to an external diameter of a large-diameter nozzle FNL compatible with the fuel device. The operation member 51 of the discriminating portion 50 guides the small-diameter nozzle intended to insert into the second portion to be inserted into the first portion. The abutting member 57 prevents a tip of the small-diameter nozzle from passing the first portion. The open/close member 70 is caused to enter an open state by the large-diameter nozzle passing through the second portion of the discrimination opening GL.