An alkoxysilyl group-containing azo compound represented by the following formula (1), a method for easily obtaining the alkoxysilyl group-containing azo compound, and a rubber composition having improved heat build-up characteristic and the like obtained using the azo compound are provided. The alkoxysilyl group-containing azo compound is preferably obtained by reacting a compound represented by the following formula (2) and a compound represented by the following formula (3): HS—(CH2)m—Si(OR1)n(R2)3-n  (3) wherein R1 and R2 represent an alkyl group having from 1 to 3 carbon atoms, R3 and R8 represent an alkylene group having from 1 to 3 carbon atoms, R4, R5, R6 and R7 represent hydrogen or an alkyl group having from 1 to 3 carbon atoms, n is an integer of from 1 to 3, and m is an integer of from 1 to 5.