Abstract: A resin composition for electromagnetic wave absorber may have large absorbance of electromagnetic wave, small transmittance and reflectance of electromagnetic wave, and small variation of reflectance depending on frequency of electromagnetic wave. An electromagnetic wave absorber may use such a composition. The resin composition may contain 0.1 to 10.0 parts by mass of an electromagnetic wave absorbing material, per 100 parts by mass of a thermoplastic resin, demonstrating an absorbance at 76.5 GHz frequency of 40.0 to 100%, when formed to a size of 150 mm×150 mm×2 mm thick and determined by Equation (A); demonstrating a difference between the maximum and minimum value of reflectance in the range from 70 GHz to 80 GHz frequency of 20.0% or smaller, when formed to a size of 150 mm×150 mm×2 mm thick and determined by Equation (B); and being suited for use as an electromagnetic wave absorber.