A tetrafluoroethylene polymer is provided in an air filter medium having a pressure loss that can be reduced and made uniform at a plurality of positions. The tetrafluoroethylene polymer may also be provided in an air filter medium, a filter pack, or an air filter unit. The tetrafluoroethylene polymer has drawability and non-melt processability. The tetrafluoroethylene polymer has a ratio S2/S1 of 0.60 or more, where S2 represents an endotherm mJ/mg in a range of T0° C. or higher and 350° C. or lower, T0° C. is a temperature 2.5° C. lower than a temperature Tp° C. (340≤Tp≤345) at which a minimum point is given on a heat-of-fusion curve obtained by measuring an unbaked polymer for measurement having no history of heating to a temperature of 300° C. or higher using a differential scanning calorimeter at a temperature-increasing rate of 2° C./min, and S1 represents an endotherm mJ/mg in a range of 320° C. or higher and T0° C. or lower.