Composition having excellent transparency

A sheet made from a polyvinyl acetal composition, comprising:

• a polyvinyl acetal satisfying at least one of definition 1 and definition 2:
• definition 1:
• when 1 g of the polyvinyl acetal is dissolved in 100 g of methanol, an undissolved content of the polyvinyl acetal is 2.5 to 90% by mass with respect to 100 parts by mass of the polyvinyl acetal, and
• definition 2:
• when 1 g of the polyvinyl acetal is dissolved in 100 g of chloroform, an undissolved content of the polyvinyl acetal is 5% to 70% by mass with respect to 100 parts by mass of the polyvinyl acetal;
• and
• 30 parts to 70 parts by mass of a plasticizer mixture with respect to 100 parts by mass of the polyvinyl acetal,
• wherein a content of the polyvinyl acetal in the sheet is 60.6% by mass or more;
• wherein the plasticizer mixture comprises:
• with respect to a total amount of the plasticizer mixture,
• 0.5% to 100% by mass of a plasticizer comprising a polar group and
• 0% to 99.5% by mass of a plasticizer comprising no polar group;
• wherein the plasticizer comprising a polar group comprises a polar group selected from the group consisting of a hydroxyl group, a polyethyleneoxide group having a polymerization degree of 10 or more, a polypropylene oxide group having a polymerization degree of 10 or more, a carboxyl group, and an amino group;
• and
• wherein the polyvinyl acetal is a polyvinyl acetal mixture of a polyvinyl acetal A and a polyvinyl acetal B having different average amounts of remaining hydroxyl groups.