A vibration mill using cog-ring media, which replaces the ball medium in a conventional vibration mill with a cog-ring medium, was developed to achieve high-impact pulverization of lignocellulosic biomass for producing bio-ethanol Japanese cedar powder pulverized by the vibration mill using cog-ring media showed that saccharification efficiency in enzymatic saccharification of Japanese cedar powder of greater than 70% was reached based on holocellulose at tube test For this study, the effect of agitation speed on enzymatic saccharification was investigated using a pulverized Japanese cedar powder Enzymatic saccharification was conducted at 10% solid concentration with agitation speeds of 0, 10, 30, 50, and 100 rpm using two scales of reactors, with 1 L and 3 L separable flasks, during 48 hr A Hi-F mixer, which was suitable for agitation of high-viscosity liquid, was used for agitation in enzymatic saccharification The enzyme of cellulase was dosed 0 5, 1, or 5% based on the weight of pulverized Japanese cedar powder Results show that the saccharification efficiency increased concomitantly with decreasing agitation speed until 30 rpm The best yields of 77% at 1 L and 75% at 3 L were obtained at 30 rpm agitation Moreover, relation between Reynolds number for mixing and saccharification efficiency was discussed to find good index for enzymatic saccharification by agitation