A composition for forming a transparent film, comprising photocatalytic particles; zirconium ammonium carbonate; a cohydrolysis-polycondensation product of an aluminum alkoxide represented by the formula Al(OR).sub.3 where R is an organic group and a titanium alkoxide represented by the formula Ti(OR').sub.4 where R' is an organic group; and water, and having a pH of 7 to 9.