To provide a thermoplastic resin composition capable of imparting sufficient hygroscopicity, etc., to a thermoplastic resin without deteriorating various characteristics of the thermoplastic resin and keeping the characteristics (hygroscopicity, etc.), over a long period (in other word, having excellent durability).

The thermoplastic resin composition contains a thermoplastic resin having at least one kind of functional group selected from carboxy group, hydroxy group and amino group and a vinylpyrrolidone copolymer having a functional group reactive with the functional group of the thermoplastic resin. The functional group of the vinylpyrrolidone copolymer is at least one kind of group selected from oxazoline group, oxazine group, epoxy group, carboxy group, amino group, acid anhydride group and isocyanate group.