Provided is a calcium carbonate that comprises crystals having a particular shape and structure and has a nano-order average particle size. Provided are a method for producing a calcium carbonate that comprises crystals having a particular shape and structure and has an average particle size in a particular range and a crystal growth method. The calcium carbonate has the calcite structure, has a BET specific surface area of 2 to 50 m2/g, has a number-based average particle size of 30 nm to 1.0 μm as determined by electron microscopy, and partially comprises substantially ring-like particles.