The effects on the size selectivity for Muraenesox cinereus caught by coastal longline fishery were investigated in the southern coast of Korea from June 2 to 17, 2019. Four sizes of hooks (sizes 15, 17, 18 and 19) and two sizes of bait (sizes 9.9 g and 18.3 g) were tested in seven and three fishing trials, respectively. Such results revealed that smaller hook and bait size improved capture efficiency. And our results demonstrate that there was no significant size selectivity effect for hook size (ANOVA, p>0.05), but small bait improved on catching smaller fish (ANOVA, p<0.05).