Concerns about magnetic effects on the biological system are growing since the chances for mankind to be exposed to moderate or strong magnetic field, e.g., linear motor cars and MRI, are increasing. Living organisms are functioned by series of chemical reactions, and, therefore, basic knowledge of the magnetic effects on fundamental chemical reactions is required for understanding the effect of a magnetic field on human health. In our studies on the effects of a magnetic field on chemical reactions, superconductive NMR instruments (400MHz) have been used. They can produce a strong and extremely stable magnetic field (9.4T [tesla]). Using these apparatus, we examined the magnetic field effects on several fundamental organic reactions. The results obtained by the present study are summarized as follows: 1) An S_N2 reaction of phenethyl mesylate with sodium iodide to produce phenethyl iodide and an epoxidation of an olefin with mCPBA are unaffected by 9.4T magnetic field. 2) Tributyltin hydride reduction of phenethyl iodide, benzyl bromide, and m-methoxybenzyl bromide is remarkably accelerated by 9.4T magnetic field. 3) A radical oxidation of benzyloxymethylene group with 1-(tert-butylperoxy)-1,2-benziodoxol-3(1H)-one, a hypervalent iodane reagent, is accelerated by both 9.4T and 7.05T magnetic field. 4) Autoxidation of linoleic acid is faster under 9.4T magnetic field than that in the absence of magnetic field.