A composition including a polytetrafluoroethylene and a polymer (I) containing a polymerization unit (I) based on a monomer represented by the following general formula (I), the composition having a standard specific gravity of 2.200 or less: CX1X3═CX2R(—CZ1Z2-A0)m   (I) wherein X1 and X3 are each independently F, Cl, H, or CF3; A0 is an anionic group; X2 is H, F, an alkyl group, or a fluorine-containing alkyl group; R is a linking group; Z1 and Z2 are each independently H, F, an alkyl group, or a fluorine-containing alkyl group; and m is an integer of 1 or more.