Provided are a chloroprene-based block copolymer, a latex, a latex composition, and a rubber composition with which it is possible to obtain a molded body having excellent tensile strength at break and tensile elongation at break even with use of less or no vulcanizing agent or vulcanization accelerator.
A chloroprene-based block copolymer including 30 to 60% by mass of a polymer block (A) derived from a monomer that can yield a polymer with a glass transition temperature of 80°C or higher when homopolymerized and 40 to 70% by mass of a chloroprene-based polymer block (B) having a chloroprene monomer unit and a polyfunctional monomer unit.