The determination method of minimum fluidization velocity from the linear regression of standard deviation of pressure fluctuation according to air velocity was investigated with binary mixture of sand and PMMA in a 0.109m I.D. fluidized bed. The experiments were performed with change of operating variables such as the fraction of flotsam and particle size, and the measured values of the minimum fluidization velocity were compared with those obtained by the other researchers. The air velocity for this method has limited from well mixed region to freely bubbling region in a fluidized bed. The optimal measuring height of pressure fluctuations seems to be at middle levels on the axis of a bed, where the solid is well mixed.