[Problem] To provide an anion exchanger which is able to be used as an ion conductivity-imparting agent that is used in a fuel cell and a water electrolysis apparatus that use an anion exchange membrane, and which is capable of achieving a good balance among heat resistance, and insolubilization and ion exchange capacity increase of the ion conductivity-imparting agent. [Solution] Heat resistance is imparted by using a styrene polymer wherein the chain length of an alkyl group between an ion exchange group and an aromatic ring is extended, and a good balance between insolubilization and high ion exchange capacity is able to be achieved by using a crosslinked structure that has a quaternary ammonium group as an ion exchange group.
