A gasket of the invention is attached to a fuel cap and is located between
a pipe sealing face of an inlet opening and a seal support element of the
fuel cap to seal the fuel cap from the inlet opening. The gasket has a
gasket main body and multiple sealing projections protruded from the
gasket main body. The multiple sealing projections include a first pipe
sealing projection and a second pipe sealing projection, which come into
contact with the pipe sealing face, and a first body sealing projection
and a second body sealing projection, which come into contact with the
seal support element. The first pipe sealing projection is formed on a
lower end of the gasket main body in its axial direction and is protruded
to be pressed against the pipe sealing face in an initial stage of a
closing operation. The second pipe sealing projection is protruded to
have a greater sealing face pressure than the first pipe sealing
projection and to be pressed against the pipe sealing face after the
initial stage of the closing operation. The gasket of the invention
ensures a sufficiently high sealing face pressure even with a small
compressive force.