Toilet lid device

A toilet lid device, comprising:

• a casing;
• a toilet seat and a toilet lid rotatably supported with respect to the casing;
• and
• a first support portion and a second support portion rotatably supporting the toilet lid with respect to the casing,
• the casing including a front surface and a rear surface opposite to each other, a left side surface and a right side surface opposite to each other and each connected to the front surface and the rear surface, and a first groove and a second groove provided on the rear surface, the first groove and the second groove being provided between the left side surface and the right side surface of the casing, the first groove and the second groove being not exposed on the left side surface and the right side surface and being exposed on an upper surface of the casing connected to each of the left side surface and the right side surface,
• the toilet lid including a first hinge portion and a second hinge portion, the first hinge portion being connected to the first support portion in the first groove, the second hinge portion being connected to the second support portion in the second groove,
• the first groove and the second groove being opened at the rear surface of the casing, and not opened at the front surface of the casing, and
• in a state of the toilet lid opened, a distance between the forward end of the first hinge portion and a forward end of the first groove being longer than a distance between a lateral end of the first hinge portion and a lateral end of the first groove,
• wherein in a state of the toilet lid opened, an upper surface of the first hinge portion is flush with the upper surface of the casing.