To improve conformability of an end part in the carrying direction of a sheet.

This sheet after-treatment device is furnished with a catching means 20 to catch an upstream end part in the carrying direction of the sheet loaded on a loading means 38, a first carrier conforming means 71 to carry the sheet on the loading means 38 toward the catching means, a second carrier conforming means 19 to conform the upstream end part of the sheet by making the sheet contact with the sheet catching means by carrying it by the conforming means 71, a width conforming means to conform a sheet bundle loaded on the loading means in a direction crossing with the carrying direction of the sheet and a control means to conform an end part in the carrying direction of the sheet by making the sheet discharged on the loading means contact with the catching means by working and controlling the first and second carrier conforming means, to conform width of the sheet by working and controlling the width conforming means and to conform an end part in the carrying direction of the sheet by making the sheet contact the catching means again by working and controlling the first carrier conforming means.