Provided is a material that can be easily biaxially oriented, homogeneously stretched even with a high draw ratio, and formed into a polytetrafluoroethylene porous membrane with low pressure loss. The present invention relates to a polytetrafluoroethylene mixture comprising: a modified polytetrafluoroethylene; and a fibrillable polytetrafluoroethylene homopolymer, the modified polytetrafluoroethylene having an extrusion pressure to a cylinder, at a reduction ratio of 1600, of 70 MPa or higher.