Vehicle seat

A vehicle seat installed with a vehicle occupant restraining device, the vehicle seat comprising:

• a seat cushion frame forming a frame of a seat cushion, and including a seat cushion side frame that extends in a seat front-rear direction at a seat transverse direction end portion;
• a seatback frame supported swingably about a reclining rod, the reclining rod extending in a seat transverse direction at a seat rear end side of the seat cushion frame, the seatback frame extending toward a seat upper side from a seat rear end side of the seat cushion frame, and the seatback frame including a seatback side frame that extends in a seat vertical direction at a seat transverse direction end portion;
• an engaging portion disposed at a seat rear end side of the seat cushion side frame and at a seat lower side relative to the reclining rod, and protruding toward a seat transverse direction inner side;
• a first movable member disposed along the seatback side frame, a lower end portion of the first movable member being positioned at a seat front side of the engaging portion due to the first movable member extending toward a seat lower side;
• and
• a first driving member configured to extend the first movable member in a case in which a vehicle collision at a seat front side occurs or in a case in which a vehicle collision at the seat front side is predicted.