A seal structure for sealing a gap between a first member and a second member of an aircraft includes: a plate spring-shaped first elastic seal; and a second elastic seal. When the first member and the second member are stationary with respect to each other, the first elastic seal elastically deforms between the first member and the second member to seal the gap, whereas the second elastic seal does not seal the gap. When the first member and the second member move closer to each other and the first elastic seal is elastically deformed, the second elastic seal elastically deforms between the first member and the second member to seal the gap.