PURPOSE: To provide a new ultraviolet absorber composed of a naphtholamide compound having a specific structure, having heat-resistance and effective as an additive for a resin such as a wholly aromatic polyamide to impart the resin with high mechanical properties and light resistant durability.

CONSTITUTION: This new ultraviolet absorber is composed of a naphtholamide compound expressed by the formula I [ring A is group of the formula II (R1 is H, halogen, 1-10C alkyl or alkoxy), formula III, formula IV or formula V; Ar1 to Ar3 are aromatic group; (n) is 0 or 1; X is O or S]. The naphtholamide compound can be produced e.g. by treating 2-hydroxy-3-naphthoic acid successively with acetic anhydride and thionyl chloride and reacting with 1,4-bis(4- aminophenoxy)benzene in N-methyl-2-pyrrolidone at 100°C for 30min. A resin composition having improved mechanical properties and light resistant durability can be produced by adding 0.01-10wt.% of the absorber to a resin such as a wholly aromatic polyamide.