A new model describing the effect of the adhesive force of particles on the bed structure in a fluidized bed is proposed. Based on this model, equations for estimating the minimum fluidization bed voidage and gas velocity were analytically derived as functions of the particle size and the adhesive force of particles. From a comparison of theoretical values with experimental values obtained in silica sand beds with various particle sizes at temperatures up to 873 K, the analytical equations were found to give excellent predictions. The predicted values were also found to agree well with the experimental values of bed voidage at ambient conditions by Leva.