To provide an antistatic agent having good transparency together with good permanent antistatic properties and mechanical characteristics for use in a molded article and to provide a thermoplastic resin composition in viewing that, while retaining transparency of an article, a conventional resin composition giving permanent antistatic properties to a transparent thermoplastic resin molded article involves the problem of deteriorating mechanical characteristics of the article, because its antistatic agent has poor dispersibility to a thermoplastic resin.

The antistatic agent is obtained from a block polymer consisting of an amide group-containing hydrophobic polymer composed of a polyamide and/or a polyamideimide, a polyether-containing hydrophilic polymer composed of a polyether diol and/or a polyether diamine and a polyester containing an aromatic ring, and is characterized by having 2-30 mJ/mg crystallization heat at the peak of crystallization measured by a differential scanning calorimeter. The antistatic resin composition is obtained by adding the antistatic agent to a transparent thermoplastic resin.