NOVELTY - Primer set for determining barnacle species, comprises (A) primer pair capable of detecting Balanus amphitrite (Amphibalanus amphitrite) comprising oligonucleotide containing 57 base pair sequence (SEQ ID NO: 1) fully defined in the specification and base pair sequence of SEQ ID NO: 2, and (B) primer pair capable of detecting Balanus albicostatus (Fitsulobalanus albicostatus) comprising oligonucleotide containing 32 base pair sequence (SEQ ID NO: 3) fully defined in the specification and base pair sequence of SEQ ID NO: 4.    USE - The primer set is useful for determining barnacle species and quantifying barnacle larva population including Balanus amphitrite, B.albicostatus B.kondakovi, B.reticulates, Megabalanus coccopoma, B.trigonus, Tetraclita japonica, Chthamalus challengeri, B.eburneus, B.improvisus, Megabalanus volcano or M.rosa (all claimed) which adheres on cooling system, sea construction, thermal and nuclear power station or fishing net.    ADVANTAGE - The method is simple, reliable and eco-friendly, and enables to detect and quantify barnacle larva visually.    DETAILED DESCRIPTION - Primer set for determining barnacle species, comprises (A) primer pair capable of detecting Balanus amphitrite (Amphibalanus amphitrite) comprising oligonucleotide containing 57 base pair sequence (SEQ ID NO: 1) fully defined in the specification and base pair sequence of SEQ ID NO: 2, (B) primer pair capable of detecting Balanus albicostatus (Fitsulobalanus albicostatus) comprising oligonucleotide containing 32 base pair sequence (SEQ ID NO: 3) fully defined in the specification and base pair sequence of SEQ ID NO: 4, (C) primer pair capable of detecting B.kondakovi (F.kondakovi) comprising oligonucleotide containing base pair sequence of SEQ ID NO: 5 and 6, (D) primer pair capable of detecting B.reticulates (A.reticulates) comprising oligonucleotide containing any one of 33 base pair sequence of SEQ ID NO: 7 and 8 fully defined in the specification, (E) primer pair capable of detecting Megabalanus coccopoma comprising oligonucleotide containing 34 and 37 base pair sequence (SEQ ID NO: 9 and 10) fully defined in the specification, (F) primer pair capable of detecting B.trigonus comprising oligonucleotide containing base pair sequence of SEQ ID NO: 11 and 12, (G) primer pair capable of detecting Tetraclita japonica comprising oligonucleotide containing base pair sequence of SEQ ID NO: 13, and a 39 base pair sequence (SEQ ID NO: 14) fully defined in the specification, (H) primer pair capable of detecting Chthamalus challengeri comprising oligonucleotide containing base pair sequence of SEQ ID NO: 15, and a 37 base pair sequence (SEQ ID NO: 16) fully defined in the specification, (I) primer pair capable of detecting B.eburneus (A.eburneus) and B.improvisus (A.improvisus) comprising oligonucleotide containing base pairs sequence of SEQ ID NO: 17, and a 38 base pair sequence (SEQ ID NO: 17) fully defined in the specification, (J) primer pair capable of detecting Megabalanus volcano comprising oligonucleotide containing base pairs sequence of SEQ ID NO: 19 and 20, and (K) primer pair capable of detecting M.rosa, comprising oligonucleotide containing base pairs sequence of SEQ ID NO: 21 and 22. ctaatgaaactaactgccaac (SEQ ID NO: 2), cacctttacttgaagtcaatggttctacc (SEQ ID NO: 4), cctataaacgatgagccacgagttac (SEQ ID NO: 5), gtacacaagatagagctctcatcaagc (SEQ ID NO: 6), accacgaattaccctactttttc (SEQ ID NO: 11), ttgaatttttcatttatgaaagttlttctg (12), acgagggacgtaactttctttgg (SEQ ID NO: 13), tgtaaacgatgagccacgaaaggc (15), gccctataaacgatgaaccacgaaaatc (SEQ ID NO: 17), atttagaggaacctgccctgtg (SEQ ID NO: 19), gacttttcatgtactttatccgttttac (20), gaccctacttttactagtacc (SEQ ID NO: 21) and gaagtccatgattttatcatgcg (SEQ ID NO: 23) INDEPENDENT CLAIMS are included for the following:    (1) determining species of barnacle larva, involves carrying out PCR in using one or more primer pairs of the above primer set, and determining species barnacle larva in the test sample by detecting the presence or absence of gene amplification of the test sample;    (2) quantifying barnacle larva population, involves performing the above process, and determining the presence of barnacle larva population by detecting gene amplification product of barnacle species in the test sample and comparing with analytical curve which is obtained using the relationship between barnacle larva population and amount of gene amplification; and    (3) kit for determining barnacle species, comprising probe containing at least one of the above primer pairs.