A bipolar plate is disposed between a positive electrode and a negative electrode of a redox flow battery. The bipolar plate has, in a surface of the bipolar plate facing at least one of the positive electrode and the negative electrode, a plurality of grooves through which an electrolyte flows and a ridge positioned between the adjacent grooves. The bipolar plate includes rough surfaces which are disposed in at least parts of groove inner surfaces defining the respective grooves and surface roughness of which represented by arithmetic mean roughness Ra is 0.1 μm or larger.