Provided is a pressure control apparatus in which workability in assembly of a body, a spool valve, a retainer, and an elastic member is improved and a high degree of freedom in a design of installation of the spool valve is obtained. A pressure control apparatus includes: a body having an opening portion penetrating a wall portion which demarcates a spool hole; a spool valve that is disposed displaceably in the spool hole; a plate-shaped retainer disposed at one end side of the spool valve in an axial direction in the spool hole; and an elastic member 6 disposed between the spool valve in the spool hole and the retainer. The retainer has a wide portion and a narrow portion. The opening portion has a first opening portion that allows the retainer to pass through and a second opening portion that inhibits the retainer from passing through.