Abstract-The essential cause of Multiple Sclerosis (MS) remains to be unknown until present. Although the relevance of racial, genetic, immunological and environmental causal factors has been accepted and expressed by various researchers, there has not been an elaborate study as to the essential cause of MS. This study aims to explain the importance of the environmental causal factor on the occurrence of MS compared to the racial, immunological and genetic factors. In this study, especially the Extreme Low Frequency (ELF) electromagnetic fields and electromagnetic fields at a frequency band (10 9 -10 13 ) Hz in terms of dielectrophoretic effect on myelin in dispersive gray matter and white matter are regarded as the essential causal factor of MS regardless of the fact, whether their sources are artificial or natural. There are epidemiological and experiment-based studies that support this view. In order to support my view, I made use of several comparative studies and obtained computational data. Dielectrophoretic force in the human body, especially in gray and white matter can affect on the myelin basic proteins and be the cause of accumulating them.