The numbers of nymphs and adults of the peach silver mite, Aculus fockeui, consumed by females of the two phytoseiid mites, Amblyseius sojaensis and A. eharai, were 9.2 and 13.3, respectively, when feeding was observed for 10 min. Functional responses of the two phytoseiid mites to the density of A. fockeui showed saturation curves, in which the maximum number of A. fockeui consumed per female per day was estimated to be ca. 300 and 400 for A. sojaensis and A. eharai, respectively. Thus, the two phytoseiid mites had great abilities to prey on A. fockeui, although the ability of A. sojaensis was somewhat inferior to that of A. eharai.