Fuel tank lid unit

The fuel tank lid unit is provided with a tank lid part, an accommodation part, and an internal terminal. The tank lid part covers an opening in the upper part of a fuel tank. The accommodation part is provided to the upper part of the tank lid part, and accommodates an electronic circuit in an internal space. The internal terminal penetrates the tank lid part, and connects an electronic componentinside the fuel tank with the electronic circuit. The accommodation part has a communication port for communicating the internal space and the exterior space. The internal space of the accommodationpart has a first area in which the electronic circuit is disposed, and a second area which is provided below than the first area and surrounds the internal terminal. When the accommodation part is seen in plan view, the surface area of the second area is smaller than the surface area of the first area. The communication port is provided below the end part on the first-area-side of the second area. 燃料箱盖单元包括箱盖部、收纳部以及内部接线端子。箱