An object of the present invention is to provide an allele specific primer
which is accompanied by less possibility of the false positive and
enables definite discrimination when a base immediately adjacent to on
the 3' side of a target SNP base is A, while a base adjacent with one
base spaced apart is A. According to the present invention, the 3' end
base is designed to be the base corresponding to SNP; the second base
from the 3' end to be C; the third base from the 3' end to be any one of
A or C; and the base sequence of from the fourth from the 3' end to the
5' end base to be completely complementary to the sequence of from a base
three bases away from the target SNP base on the 3' side to a desired
base.