The two-spotted spider mite Tetranychus urticae is being steadily problematic on strawberry. To effective control of this pest, one combination application using predatory mite Phytoseiulus persimilis plus a pesticide Acequinocyl suggests. Prepared six beds (1.5 × 3 m; 20 strawberry plants) on glass house, 100 T. urticae was inoculated on per 20 plants. Four plots prepared - Acequinocyl treatment, P. persimilis application, Acequinocyl+P. persimilis double application, and the control. The change of T. urticae density was investigated in the seven-day intervals. In an Acequinocyl treated plot, T. urticae density was decreased after Acequinocyl sprayed, but began to increase steadily one month later. In a P. persimilis applied plot, T. urticae density began to decrease at 20 days after P. persimilis inoculation. In an Acequinocyl + P. persimilis double applied plot, T. urticae density was dramatically decreased after application and then no found the T. urticae. To practical use in farmhouse, it will be possible to control by inoculation of P. persimilis only when low density of T. urticae; however, double application with spray pesticide Acequinocyl plus apply the natural enemy P. persimilis will be good when high density of T. urticae.