The pressure control valve comprises a negative pressure valve and a positive pressure valve. The negative pressure valve comprises a negative pressure valve body, a valve retaining member and an engagement mechanism. The engagement mechanism comprises a support concave portion formed on the negative pressure valve body and a support protrusion formed on the valve retaining member and inserted into the support concave portion, which is formed to reduce the elastic deformation transferred to a second seating portion, when a first seating portion is pressed by a first seal portion to undergo elastic deformation.