An apparatus for controlling a discharge pressure of a fluid includes: a pump configured to suck the fluid through an inlet or to discharge the sucked fluid through an outlet; a distributor connected to the pump and to an injection nozzle provided by a sensor and configured to distribute the fluid discharged from the pump to the sensor; and a controller. The controller is configured to control the pump to operate selectively in accordance with detection of contamination of the sensor and to control operation of the distributor to be forcibly delayed during operation of the pump such that the fluid distributed to the sensor, when detected as being contaminated, is controlled to reach a selected required discharge pressure of different required discharge pressures selected in accordance with water amount information and a degree of contamination of the sensor.