The glass sheet production method of the present invention includes the steps of (I) bringing a first acid gas into contact with at least one principal surface of a sheet-shaped glass material, the first acid gas containing hydrogen fluoride (HF) gas but not containing hydrogen chloride (HCl) gas and having a volume ratio of water vapor to HF gas of less than 8, the glass material containing at least sodium as a component and having a temperature in a range from a glass transition temperature to a temperature 250°C higher than the glass transition temperature; (II) before or after the step (I), bringing a second acid gas into contact with the principal surface of the sheet-shaped glass material, the second acid gas containing HCl gas and optionally containing HF gas, wherein when the second acid gas contains both HCl gas and HF gas, the second acid gas further contains water vapor with a volume ratio of water vapor to HF gas of 8 or more; and (III) cooling the sheet-shaped glass material having undergone both the step (I) and the step (II) so as to obtain a glass sheet.