To provide a gas barrier sheet with a moisture absorbing layer showing excellent moisture absorbing properties, and a method for manufacturing this sheet.

This gas barrier sheet 1A has a base 2 and the moisture absorbing layer 3 formed on the base 2. In addition, the moisture absorbing layer 3 contains an alkali metal oxide or an alkali earth metal oxide, and the maximum difference of elevation (Rmax) of the surface of the gas barrier sheet 1A is reduced to 1,000 nm or below. Further, the moisture absorbing layer 3 can be formed through the process for forming the moisture absorbing layer on condition that the required temperature be lower than a room temperature (25C).