A seat structure includes: a seat main body; a seating surface element attached to the seat main body, and extending in a longitudinal direction; a back element connected to a rear end of the seating surface element in a reclinable manner, and extending in a vertical direction; an upper end flap connected to an upper end of the back element in a forward tiltable manner; a displacement member supported on the back element in a vertically displaceable manner; and a first connection element connecting the displacement member and the upper end flap so as to tilt the upper end flap forward according to displacement of the displacement member.