An object of the present invention is to conduct a search for a compound to be arranged at a terminal of a peptide nucleic acid effective in detecting a single nucleotide polymorphism. Provided is a tolan compound represented by the following formula (1): wherein R1 represents a phenyl group or a naphthyl group, the phenyl group may have 1 to 5 substituents that are identical to or different from each other, and the naphthyl group may have 1 to 7 substituents that are identical to or different from each other.