A primer set that allows a target nucleic acid to be amplified specifically and efficiently. The primer set of the present invention includes at least two primers that allow a target nucleic acid sequence to be amplified. A first primer included in the primer set contains, in its 3′ end portion, a sequence (Ac′) that hybridizes to a sequence (A) located in the 3′ end portion of the target nucleic acid sequence. The first primer also contains, on the 5′ side of the sequence (Ac′), a sequence (B′) that hybridizes to a complementary sequence (Bc) to a sequence (B) that is present on the 5′ side with respect to the sequence (A) in the target nucleic acid sequence. A second primer included in the primer set contains, in its 3′ end portion, a sequence (Cc′) that hybridizes to a sequence (C) located in the 3′ end portion of a complementary sequence to the target nucleic acid sequence. The second primer also contains, on the 5′ side of the sequence (Cc′), a folded sequence (D-Dc′) that contains, on the same strand, two nucleic acid sequences that hybridize to each other.