In recent years, the clinical application of electromyogram has advanced extremely. But this clinical electromyogram is located principally on the single unit electromyogram by the co-axial needle electrode. Accordingly the author has undertaken a basic study in order to clarify the clinical value of the electromyogram by the skin surface electrode. Then, for a portion of this study, the frequency spectrum of the surface electrode electromyogram had been examined by Fouriers integration analysis. (1) The pattern of the surface electrode electromyogram had been examined by function theory, and explained its meaning of the frequency sqectrum of the surface electrode electromyogram by Fouriers analysis from next stand point. Standing in this point, next theory should be recognized; the electromyogram can not mean the direct record of an action potential of a muscle fiber or a muscle fascicle, and electromyogram includes in it necessarily the variation of charactristics of the electrofield, viz. an organism (expressed as volum conductor), and the charactristics of amplifier and recorder. Those charactristics are expressed by number of coefficients by frequency. (2) The frequency spectrum of the surface electrode electromyogram fluctuates by the method of pick-up, acting state of a muscle, individuarity and etc. (3) At standerd state this frequency spectrum mainly distributes from 10c. (cycle per second) to 600c., and essential parts of this spectrum distributes from 20c. to 70c. (4) The study on the origin of those fluctuation will be explained in the next part.