A single juvenile specimen of $Thunnus$ $alalunga$ (8.4 mm in standard length) of the Scombridae was collected from the southeast sea of Jeju Island ($127.7^{circ}E$, $33.0^{circ}N$) on August 18, 2011. It was identified as $T.$ $alalunga$ based on the following combination of morphological characters: snout elongated; melanophores focused on the dorsal spiny region, but no melanophores on the dorsal soft fin base, anal fin base or caudal region.