One aspect of the sheet-like air cell of the present invention includes a positive electrode having a catalyst layer, a negative electrode, a separator, and an electrolyte solution that are housed in a sheet-like outer case. The electrolyte solution is an aqueous solution that contains an electrolyte salt and has a pH of 3 or more and less than 12. The electrolyte solution contains a water-soluble high-boiling solvent with a boiling point of 150° C. or more in an amount of 3 to 30% by mass of the total solvent. Another aspect of the sheet-like air cell of the present invention includes a positive electrode having a catalyst layer, a negative electrode, a separator, and an electrolyte that are housed in a sheet-like outer case. The electrolyte is obtained by blending an electrolyte solution and a thickening agent. The electrolyte solution is an aqueous solution that contains an electrolyte salt and has a pH of 3 or more and less than 12.