Films containing polyvinyl acetal

Acetalization degree of 50 to 85 mol%, 0.1 to 20 mol% content of vinyl ester monomer units, a film with viscosity average degree of polymerization contains a polyvinyl acetal which is 200 to 2000, said film the content of plasticizer in is less than 10 parts by mass per 100 parts by weight of polyvinyl acetal, and the film satisfies the following formula (1) and (2). (A-B) / A <0.80 (1) Thus, less coloration due to heating, foreign objects on top (undissolved) is small, long-term moisture permeability be used is provided is less likely to film increases.