Abstract: A toilet stool capable of being seated for use in defecation or urination, and a toilet stool for use in defecation or urination which is characterized by mounting a toilet seat whose opening width can be varied. The toilet stool comprises a toilet seat having two foliar plates capable of freely falling onto the upper surface of a peripheral edge portion of the toilet stool as a pedestal and a toilet lid mounted on the toilet seat; wherein the foliar plates of the toilet seat is linked to the driving portion of the rear portion of the toilet seat so that the foliar plates of the toilet seat vary the opening width of the toilet seat.