To provide a flame-retardant electromagnetic interference suppressor formed of complex of an organic binder which does not contain halogen, and soft magnetic powder, is easy to form in a sheet, does not generate gas, and exhibits high real part permeability and tensile strength which is not subject to the Export Trade Control Order.

The electromagnetic interference suppressor 1 is formed by dispersing the soft magnetic powder 2 in the flame-retardant organic binder 3. A surface of the soft magnetic powder 2 is previously treated by a silane coupling agent.