By a method for manufacturing a flat image display device having a plate spacer, even if the center of the plate spacer is displaced from its initial assembly position, it can easily be corrected to the initial assembly position again, allowing stable production of high-quality image display devices. The present invention includes the process of forming a space between the plate spacer and a first substrate between the process of fixing the plate spacer to the first substrate and the process of tightly bonding the first substrate and a second substrate together.