As for the reason why many Shujikan were built in Hokkaido, it has been said that there was an intention to keep prisoners to stay in Hokkaido after their release in order to increase Hokkaido's population which was fewer at that time.
北海道に多くの集治監が作られた背景は、出所後も現地に留まらせ、当時少なかった人口の増加につなげる思いもあったと伝えられる。