Provided are a curable composition including a compound expressed by General Formula (1) below; a polymerization initiator; and a chain transfer agent, and a cured polymer product. In General Formula (1), m represents an integer of 1 to 4, and n represents an integer of 1 to 4. Here, a sum of m and n is not greater than 5. MA represents a hydrogen ion, an inorganic ion, or an organic ion. Here, an inorganic ion and an organic ion may be bivalent or higher ions. Each of R1 and R2 independently represents a hydrogen atom or an alkyl group.