As described above, the heating wire 8 is constituted by the first terminal portion 81, the first wire portion 83, the second wire portion 84, the third wire portion 85, and the second terminal portion 82 that are connected in series to the power source (constant voltage). Also, heat is generated by applying a current, and thus it is possible to prevent the opening 43 from fogging up, and to remove fog that has occurred.

There is no particular limitation on the width of the heating wire 8, and the width of the first, third, and fifth parts 85a, 85c, and 85e that are located in the opening 43 is preferably 50 to 1000 μm, and more preferably 200 to 500 μm. Note that portions located in the opening 43 can be seen from the outside of the vehicle. That is, if the blocking layer 4 is layered on a surface on a vehicle interior side of the inner glass plate 12 and a surface on the vehicle interior side of the outer glass plate 11, for example, even if the heating wire 8 is disposed on a portion of at least one of these surfaces that corresponds to the blocking layer 4, the portions of the parts that can be seen from the outside of the vehicle preferably have a width such as that described above. Hereinafter, this portion may be referred to as an “exposed portion”.

On the other hand, the second and fourth parts 85b and 85d, the first wire portion 83, and the second wire portion 84 that are located outside the opening 43 preferably have a width of 50 to 5000 μm, and more preferably has a width of 200 to 100 μm so as to be concealed by the blocking layer 4. Hereinafter, this portion may be referred to as a “concealed portion”.