Provided is a monomer mixture that is rapidly cured to form a cured product having high hardness, excellent alkali resistance, and excellent adhesion to a substrate. The monomer mixture of the present invention is a monomer mixture containing at least: a compound represented by Formulas (a-1) and/or (a-2); a compound (2B) including two cationically polymerizable groups per molecule, at least one of the cationically polymerizable groups being an epoxy group; a compound (3B) including three or more cationically polymerizable groups per molecule, at least one of the cationically polymerizable groups being an epoxy group; and a compound represented by Formula (c-1).