CT-processing is very effective in obtaining 3-dimensional information for industrial instruments, and several trials have also been applied to fluidized-beds. In the CT-processing of fluidized-beds, X-rays are used mainly because they are readily availability. Similar processing can be performed by neutron-rays which penetrate most metals, but not some chemical substances, such as hydrogen, boron, gadolinium, which are opaque to the neutrons. Due to these unique characteristics, neutron radiography can be considered as a suitable visualization method of actual industrial instruments made of metal. Thus, neutron radiography also has significant advantages for the visualization of fluidized-beds. However, neutron radiography requires a nuclear reactor or an accelerator as the neutron source in order to obtain high quality images, which means that the real time CT-processing of multiphase flows by neutron radiography is quite difficult. Consequently, CT-images in this investigation were reconstructed by using time-averaged visualization images. Although time averaging makes the understanding of the void movement difficult, 3-dimensional characteristics of the void fraction propagation in fluidized-beds could be clearly visualized by using test sections with significant non-uniformity of the fluidized-gas distribution.