An Eulerian/Lagrangian-type numerical simulation was performed on a two-dimensional fluidized bed in which the particle motion is restricted by parallel front and rear walls. Particle motion was calculated using Newton's equation of motion, and the contact forces were modeled by the discrete element method. The locally averaged equations were solved to calculate the fluid motion, taking into account the interaction between fluid and particles. Two kinds of models were used regarding the calculation of the particle motion : a two-dimensional model and a three-dimensional model. Results for both cases were compared with each other and the effect of the walls on the particle motion is discussed. Cases where partition walls are set up artificially in the bed are also calculated.