An objective of the invention is to provide a rubber composition which has satisfactory processability and dimension stability, and the like, gives a vulcanized rubber exhibiting excellent wearing resistance and tensile strength, and the like, and thus is useful in a belt, a hose and a tire and the like, as well as a crosslinked rubber particle for obtaining such rubber composition. A rubber composition of the invention comprises [1] a crosslinked rubber particle comprising as repeating units (a) 30 to 94.89% by weight of a conjugated diene unit, (b) 5 to 69.89% by weight of an aromatic vinyl unit, (c) 0.01 to 10% by weight of a monomer unit having at least two polymerizable unsaturated group, (d) one polymerizable unsaturated group and an amino group, a hydroxyl group and an epoxy group and (e) 0.1 to 30% by weight of a monomer unit having one polymerizable unsaturated group and a carboxylic group and having a particle size of 10 to 500 nm and a toluene-insolubles of 80% by weight or more and [2] a non-crosslinked rubber component whose toluene-insolubles is less than 20% by weight.