A fuel pressure adjusting apparatus which includes a casing which includes a fuel introduction port, and a fuel discharge port; and a cylindrical member which is housed in the casing, and which includes a valve seat at an end portion thereof, and a communication passage therein, the communication passage connecting the fuel introduction port to the fuel discharge port; a valve element which is provided on a fuel discharge port-side of the valve element in the casing, and which closes the communication passage when the valve element is seated on the valve seat; and a leaf spring which is provided at the fuel discharge port, and which applies force to the valve element in a direction toward the valve seat. The leaf spring includes a concave portion which supports the valve element, and which is formed such that there is a gap between the concave portion and the valve element.