The present invention relates to a rubber composition comprising 100 parts by mass of a solid diene-based rubber (1), 5 to 150 parts by mass of silica (2), 0.1 to 50 parts by mass of a liquid diene-based rubber (3) which is modified with an unsaturated carboxylic acid and/or derivative thereof and has a number average molecular weight of 5000 to 100000, and further 0,1 to 50 parts by mass of an unmodified liquid diene-based rubber (4) having a number average molecular weight of 5000 to 100000 with respect to 100 parts by mass of the solid diene-based rubber (1) and/or 1.5 to 14.0 parts by mass of water (5) with respect to 100 parts by mass of silica (2), and a crosslinked product obtained by crosslinking the rubber composition.A rubber composition obtained by the present invention is improved in processability when silica is added and mixed with a diene-based rubber and is excellent in dynamic properties after crosslinking.