Provided is a composition for an electrochemical device functional layer with which it is possible to form a functional layer for an electrochemical device that has excellent wet adhesiveness and that can cause an electrochemical device to display high output characteristics. The composition for an electrochemical device functional layer contains a particulate polymer having a volume-average particle diameter of not less than 0.5 μm and not more than 10 μm and a degree of swelling in electrolyte solution of 120% or less.