The invention relates to: a modified rubber having a specific structure modified with a compound having two or more epoxy groups in the molecule; and a process for producing a modified rubber which includes copolymerizing a vinylaromatic hydrocarbon and a conjugated diene by the solution polymerization method using an organolithium as an initiator and modifying the resultant copolymer with a compound having two or more epoxy groups in the molecule. The invention further relates to a modified-rubber composition obtained by compounding a raw rubber containing the modified rubber with silica, and to rubber vibration isolators and a footwear article each obtained from the modified-rubber composition.