Provided is a pressure control device for stably controlling the internal air pressure of a reservoir. The pressure control device includes: an input terminal receiving source air pressure; an intake valve connected between the input terminal and an output terminal; an exhaust valve connected to the output terminal; a pressure sensor connected to the output terminal and generating a sensed value by sensing pressure at the output terminal; and a controller simultaneously operating the intake valve and the exhaust valve by simultaneously operating a first control loop for adjusting the degree of opening of the intake valve by comparing the sensed value with a first target value and a second control loop for adjusting the degree of opening of the exhaust valve by comparing the sensed value with a second target value.