A method for manufacturing a rubber product comprising: - A) heating an uncrosslinked rubber composition containing: a hydrogen-containing fluororubber; a thermal crosslinking agent that crosslinks the hydrogen-containing fluororubber when heated to a predetermined temperature; wherein said thermal crosslinking agent is a peroxide; and a hydrogen site protective agent that bonds to carbon radicals resulting from breakage of carbon-hydrogen bonds of the hydrogen-containing fluororubber which occurs under irradiation, wherein said hydrogen site protective agent contains a compound with a perfluoro skeleton having an alkenyl group that bonds to the carbon radical of the hydrogen-containing fluororubber in its molecule and a compound with a siloxane skeleton having an alkenyl group that bonds to a carbon radical of the hydrogen-containing fluororubber in its molecule, to said predetermined temperature to crosslink the hydrogen-containing fluororubber by the thermal crosslinking agent, - B) irradiating the rubber composition obtained at step A) so that the hydrogen site protective agent bonds to the carbon radicals resulting from breakage of the carbon hydrogen bonds of the hydrogen containing fluororubber to obtain the rubber product. - A) heating an uncrosslinked rubber composition containing: a hydrogen-containing fluororubber; a thermal crosslinking agent that crosslinks the hydrogen-containing fluororubber when heated to a predetermined temperature; wherein said thermal crosslinking agent is a peroxide; and a hydrogen site protective agent that bonds to carbon radicals resulting from breakage of carbon-hydrogen bonds of the hydrogen-containing fluororubber which occurs under irradiation, wherein said hydrogen site protective agent contains a compound with a perfluoro skeleton having an alkenyl group that bonds to the carbon radical of the hydrogen-containing fluororubber in its molecule and a compound with a siloxane skeleton having an alkenyl group that bonds to a carbon radical of the hydrogen-containing fluororubber in its molecule, to said predetermined temperature to crosslink the hydrogen-containing fluororubber by the thermal crosslinking agent, a hydrogen-containing fluororubber; a thermal crosslinking agent that crosslinks the hydrogen-containing fluororubber when heated to a predetermined temperature; wherein said thermal crosslinking agent is a peroxide; and a hydrogen site protective agent that bonds to carbon radicals resulting from breakage of carbon-hydrogen bonds of the hydrogen-containing fluororubber which occurs under irradiation, wherein said hydrogen site protective agent contains a compound with a perfluoro skeleton having an alkenyl group that bonds to the carbon radical of the hydrogen-containing fluororubber in its molecule and a compound with a siloxane skeleton having an alkenyl group that bonds to a carbon radical of the hydrogen-containing fluororubber in its molecule, to said predetermined temperature to crosslink the hydrogen-containing fluororubber by the thermal crosslinking agent, - B) irradiating the rubber composition obtained at step A) so that the hydrogen site protective agent bonds to the carbon radicals resulting from breakage of the carbon hydrogen bonds of the hydrogen containing fluororubber to obtain the rubber product.