The problem of computer modeling and visualization of weak electromagnetic fields is important for research activity, education, biology, medicine and industry. Visualization helps better understanding and clarifying the physical and mathematical models that are used. In medicine low frequency magnetic fields are traditionally used in magnetotherapy, and at the moment computer modeling and visualization give the only practical approach to the studying the influence of magnetic fields on a living organism. In this work we designed and implemented an effective and adequate computer tool both for modeling a magnetic field distribution and the action of the field on charged particles. The tool is designed in the program environment Unity, which allows the combining calculations and visualization, considerable reducing run-Time and the development of a flexible application that may be easily used by both practicians and researchers. The results of experiments are given.