A flush toilet includes a bowl part, a drainage water trap part that is connected to a bottom part of the bowl part, and a water drainage socket that is connected to the drainage water trap part and includes an upper side water drainage socket that extends downward from the drainage water trap part, a back side R part that is connected to the upper side water drainage socket and changes a flow channel so that a washing water that flows from an upper side is directed to a front side, and a horizontal pipe that extends forward from the back side R part. The back side R part and the horizontal pipe include a water storage part that stores a part of washing water. The water storage part is arranged on a lower side of a back side lower end part of the drainage water trap part.