Seat frame of vehicle seat

A seat frame of a vehicle seat, the seat frame comprising:

• a cushion frame including:
• a pair of side frames extending in a front and rear direction at an interval in a seat width direction and having a cross section that is a closed section;
• a front frame connecting front end sides of the pair of side frames in a bridging manner;
• a rear frame connecting rear end sides of the pair of side frames in a bridging manner;
• and
• a plate-shaped panel member disposed between the front frame and the rear frame and configured to place and support a cushion pad serving as a cushioning material thereon;
• and
• a back frame,
• wherein a lower portion of the back frame is connected to a rear portion of each of the pair of side frames, and
• wherein the panel member is formed of a material having at least one of a higher specific strength and a higher specific modulus than those of the pair of side frames, the front frame, and the rear frame, a rear end side of the panel member is attached to a lower side of the rear frame and lower sides of the pair of side frames, and a front end side of the panel member is attached to an upper side of the front frame and upper sides of the pair of side frames.