A composition for forming a protective film that is placed between a positive electrode and a negative electrode of an electrical storage device, includes polymer particles (A1), polymer particles (A2), and a liquid medium, the polymer particles (A1) including a repeating unit derived from a compound that includes two or more polymerizable unsaturated groups in an amount of less than 15 parts by mass based on 100 parts by mass of the polymer particles (A1), and the polymer particles (A2) including a repeating unit derived from a compound that includes two or more polymerizable unsaturated groups in an amount of 20 to 100 parts by mass based on 100 parts by mass of the polymer particles (A2).