A thermoplastic resin composition obtained by mixing 100 parts by weight of at least one thermoplastic resin (A) with 0.1 to 4 parts by weight of (B) a polyfunctional compound having three or more functional groups in which at least one of the terminal structures having the functional groups is a structure represented by formula (1): where R is an alkylene group with 1-15 carbon atoms; n is an integer of 1 to 10; and X is at least one functional group selected from the group consisting of hydroxyl group, aldehyde group, carboxyl group, sulfo group, amino group, isocyanate group, carbodiimide group, oxazoline group, oxazine group, amide group, silanol group and silyl ether group.