Electromagnetic forming is one of the sheet metal forming processes in which force is applied by an electromagnetic pulse. In this process, sheet metal is deformed rapidly at high strain rates. In this paper, FE simulation has been applied to study distribution of magnetic field formed by spiral coil and inducted eddy current in a circular sheet. At first, magnitude and components of magnetic field intensity have been calculated and compared with experimental results taken from literature. After verifying of simulation results, the effects of sheet thickness on magnetic force magnitude and distribution have been investigated.