Seat device

A seat device that can convert a state of a seat, comprising:

• a rotation lock mechanism that restrain the seat at each of a plurality of rotation angles, the seat being rotatable about a rotation axis;
• a rotation operation unit that performs a release operation that releases the seat from restraint by the rotation lock mechanism;
• and
• a rotation operation prevention mechanism that disables the release operation of the rotation operation unit when the seat is in a specific state at one of the rotation angles,
• the rotation operation prevention mechanism comprising:
• an engaging unit provided on a fixed side of the seat;
• and
• an engaged unit that is provided in the rotation operation unit on a movable side of the seat, and disables the release operation of the rotation operation unit by being engaged with the engaging unit when the seat is in the specific state,
• the rotation operation unit is displaced between a using position at which the release operation is enabled, and a housing position at which the release operation is disabled, and
• when the seat is in the specific state, the rotation operation prevention mechanism displaces the rotation operation unit from the normal position to the housing position, and restrains the rotation operation unit in the housing position by engaging the engaged portion with the engaging portion.