Two experiments were carried out to study the effects of magnetic force and magnetic water on two spotted spider mites Tetranychus urticae (Koch) (Acari: Tetranychidae) andits predator Amblyseius gossipi(El-Badry)(Acari: Phytoseiidae) .In The first experiment leaflets of infested soybean with T.urticae and A. gossipi were passed through  different concentrations of magnetic force  and magnetic water at different time intervals the concentrations of magnetic force and magnetic water in the laboratory were 100,200,300,400 and 500 Gausses, respectively, while Magnetic force and magnetic water in the field were 1000,2000,3000,4000 and 5000 Gausses, respectively. The second experiment was conducted by sprayed the infested leaflets with T. urticae and A. gossipi at three time intervals. The results in both experiments revealed that the  numbers of two tested mite and its predator were reduced after treated with magnetic force or magnetic water. Also, the data indicated that magnetic force was the most effect on adults and the eggs stage of T. urticae, but was the lowest toxic effect on  A. gossipi ,while magnetic water was moderate effect on eggs and adults of two tested mite and its predator. Under the field condition the magnetic force was the most effect on behavior and population of T. urticae and A. gossipi, while  magnetic water was moderate effect on the population and behavior of eggs and moile stages to T. urticae and adults of A. gossipi