To provide a rehabilitation instrument to prevent contracture of finger joints of a patient who has lost physical capabilities of fingers by nerve damage, stroke, or the like.

The rehabilitation instrument comprises an insertion part for fingers provided on a cover having a bag body having the inside where a gas or a fluid is filled/discharged and a fixing member for fixing a hand, a wrist, a lower arm, or the like. The insertion part has a mechanism to narrow the gap between the finger and the insertion part as the bag body is inflated and to fix the fingers relative to the cover.