Swarm robotics is a research field in which a group of autonomous robots execute tasks through cooperative works. Sharing information among robots is a central function for an optimal performance of the system. Given that the swarm network structure constantly changes when robots move, it becomes difficult to guarantee on information sharing by all swarm members. We, in this work, propose an approach for information sharing on swarm robotic systems by using Blockchain technology. A function of distributed ledger in Blockchain technology has possibility to solve the information sharing problem and to easily synchronize their state. However, because Blockchain persistently keeps past transactions, the increase of its chain size is one of the serious issues to manage Blockchain technology. In this paper, we introduce a methodology to share information among autonomous robots and demonstrate through experiments that how the differences in data size recorded in the blockchain affect the chain size. As a result, compared with our previous approach, we succeeded in suppressing increase in chain size by using the proposal approach; it was reduced the amount of increase in chain size about 73.0% when each node repeatedly shared about 2.8KB image data by 100 times.