The maximum magnetic flux leakage from a crack is obtained when the magnetic flux is distributed to the longitudinal direction of the crack in the orthogonal direction. In magnetic-particle testing with a yoke method, since we usually cannot predict the direction of the crack to be detected, it is necessary to perform the testing at least two times by changing the direction of magnetization. In a rotating magnetic field type magnetizer using a three-pole coil (a three-phase alternating current), omnidirectional crack can be detected by a single testing. However, the rotating magnetic field becomes no homogeneous distribution at a position far from the center of the magnetizer, and the strong magnetic field is generated in a specific direction. In this research, the multi coil magnetizer that widely obtained uniform rotating field distribution was developed. The distribution of the rotating magnetic flux density on the steel plate was evaluated with a finite element method analysis. In addition, a prototype magnetizer was produced based on the analytical results, and the characteristic was evaluated.