Problem to be solved. To provide a biocatalyst-containing substance with high efficiency in valuable material production while excellent in durability to an external force. Solution. A biocatalyst-containing substance includes a droplet containing a biocatalyst and a composite particle coating a surface of the droplet, and has a number average particle diameter d50c of 10 to 1,000 Âµm. The droplet is a solution containing water by 15 mass% or more. The composite particle includes a hydrophobic solid particle B on a surface of a hydrophobic solid particle A.