The present invention provides a coating agent having a reduced methanol content, an adhesive including the coating agent and excellent in coating performance and adhesiveness, and a coated product including the coating agent and excellent in water resistance and alcohol resistance. The present invention relates to a coating agent comprising a modified vinyl alcohol polymer (A), the modified vinyl alcohol polymer (A) comprising a structural unit derived from a derivative (a) of an ethylenically unsaturated dicarboxylic acid in a content (X) of 0.05 mol % or more and 10 mol % or less, having a degree of saponification of 80.0 mol % or more and 99.9 mol % or less, having a methanol content of less than 3.0 mass % as measured by headspace gas chromatography, and having an amount of 0.1 ppm or more and less than 2,000 ppm of a component insoluble in a 90° C., 5 mass % aqueous solution.