A method for producing low molecular weight polytetrafluoroethylene having a melt viscosity at 380° C. of 1.0×102 to 7.0×105 Pa·s. The method includes: (1) irradiating high molecular weight polytetrafluoroethylene with radiation in the presence of a substance capable of generating a free hydrogen atom and decomposing the high molecular weight polytetrafluoroethylene into a low molecular weight component; and (2) deactivating at least part of main-chain radicals and end radicals generated by the irradiation and providing the low molecular weight polytetrafluoroethylene. Also disclosed is a composition containing the low molecular weight polytetrafluoroethylene and a low molecular weight polytetrafluoroethylene.