Abstract: The present invention provides a toilet seat having a non-powered apparatus for automatically flushing a toilet using water pressure and body weight and a method for controlling the toilet seat. The toilet seat includes a weight sensor and water passage control unit (300) which senses a body weight and controls discharge of water, supplied through a pipe, depending on the turning on/off of a control valve, and a check valve unit (400) which controls the amount of water passing through a water passage from the control valve of the unit (300) depending on water pressure and displacement of the toilet. The toilet seat further includes a cylinder actuating unit (500) which is operated by pressure of water supplied from the weight sensor and water passage control unit (300) when the body weight is detected by the unit (300), thus automatically supplying water to the automatic flushing apparatus.