The predatory mite Bdellodes japonicus (Ehara) (Bdellidae) preyed on Tetranychus urticae Koch, Tetranychus truncatus Ehara, Amphitetranychus viennenis (Zacher) and Oligonychus biharensis (Hirst) (all Tetranychidae) in the laboratory. The number of spider mites consumed by Bdellodes japonicus decreased in the order of: Oligonychus biharensis > Amphitetranychus viennenis > Tetranychus urticae > Tetranychus truncatus at 25±1°C. Functional responses of Bdellodes japonicus (Ehara) to adult females of Tetranychus urticae approximated the Holling type II response. The model equations of the functional responses were Na=0.7720N0/ (1 0.0366N0) at 25±1°C and Na= 1.1243N0/(1 0.0807N0) at 30±1°C.