According to one embodiment, a toilet lid device includes a casing, and a toilet seat and a toilet lid rotatably supported with respect to the casing. A lower surface of the toilet lid covers an upper surface of the toilet seat and an upper surface of the casing in a state of the toilet lid closed. The lower surface of the toilet lid has a first lower surface parallel to the upper surface of the toilet seat and a second lower surface parallel to the upper surface of the casing.