This glass sheet manufacturing method is a method for manufacturing a glass sheet having a modified surface, and includes a gas contact step for bringing hydrogen fluoride (HF) gas and hydrogen chloride (HCl) gas into contact with at least one principal face of a glass sheet having a temperature in the range of 450-630°C. The volume ratio (volume of water vapor/volume of HF gas) of water vapor with respect to hydrogen fluoride (HF) gas in the gas including hydrogen fluoride (HF) which is used in the gas contact step is less than 8.
