A pop-up stopper includes a main body having an inside provided with a receiving space and a periphery provided with a plurality of through holes, a control unit removably mounted on a top of the main body and including a top cap and a plurality of connecting members, and a bottom cap removably mounted on a bottom of the main body. Each of the connecting members includes at least one upper elastic plate having a protrusion and at least one lower elastic plate having a protrusion. Thus, the stopper has draining and straining functions to achieve a sanitary effect. In addition, the control unit and the bottom cap can be mounted on and detached from the main body easily and quickly, thereby facilitating a user assembling and disassembling the stopper.