A rubber composition contains: at least one rubber component selected from the group consisting of an ethylene propylene diene rubber, a chloroprene rubber, a nitrile rubber, and an acrylic rubber; 1.5 to 30 parts by mass of a fluorene-modified cellulose nanofiber per 100 parts by mass of the rubber component; and 30 to 120 parts by mass of a carbon-based filler per 100 parts by mass of the rubber component. A method of producing a rubber composition comprises: kneading a dispersion of a fluorene-modified cellulose nanofiber in a process oil and a rubber component to prepare a kneaded material; and mixing a vulcanizing agent into the kneaded material.