A pressure controller for a phlegm sucking device includes a seat body, a press element and a control valve. The seat body has a containing space, a gas inlet tube and a gas outlet tube interconnected with each other. The control valve is disposed in the containing space. An upper end and a bottom end of the control valve abut the press element and an upper portion and a bottom of the seat body respectively for blocking or allowing communication between the gas inlet tube and the gas outlet tube. The control valve includes a plastic restoring element. When the plastic restoring element is deformed to have a decreased height, the plastic restoring element allows the control valve to move and provide a resilience. The control valve blocks the communication between the gas inlet tube and the gas outlet tube when the plastic restoring element is not deformed.