A design supporting apparatus of a semiconductor integrated circuit includes an input device configured to receive data of a transient current waveform, a first modeling part configured to model the semiconductor integrated circuit as a current source for generating the transient current waveform and to connect the current source and an equivalent circuit of an evaluation board to generate an evaluation circuit model, a first calculation part configured to calculate electromagnetic interference of the evaluation circuit model, a first correction part configured to correct a portion of the equivalent circuit of the evaluation board, a second modeling part configured to add an additional circuit to a corrected evaluation circuit model to generate a countermeasure circuit model, a second calculation part configured to calculate electromagnetic interference of the countermeasure circuit model, and a second correction part configured to correct the additional circuit.