Changeable-floor type rearing cage

A changeable-floor type rearing cage for rearing small animals includes a hexahedral cage body having a top wall, four side walls and a bottom wall, and defining a space for rearing small animals therein, and a drawer-type floor board inserted through a slot formed in the front side wall into the cage body and placed in the cage body so as to be cover the bottom wall and to be drawn out of the cage body, and providing a surface with which the small animals come directly into contact. At least a part of the floor board is perforated or meshed to let liquid excrements excreted by the small animals drip from the floor board.