A reflux valve includes a first supported portion that plugs a first opening when a valve body biased by a biasing member moves to one side in an axial direction, the first supported portion opens the first opening when the valve body moves to the other side in the axial direction against a biasing force of the biasing member due to negative pressure applied to a downstream side relative to an upstream side, the valve body includes a first hole extending from an end on the other side in the axial direction to one side in the axial direction, a valve body portion includes a second hole extending from an outer side in a radial direction and reaching the first hole, and the valve body portion includes a third hole at a different position from the second hole in the axial direction.