A tread rubber composition of excellent hydrophobic property and water repellency suitable to a studless tire of excellent performance on ice, comprising a diene rubber comprising at least one rubber selected from the group consisting of natural rubber, isoprene and polybutadiene as a main ingredient and, based on 100 parts by weight of the diene rubber, from 10 to 40 parts by weight of a clay comprising kaolinite as a main ingredient and having an oil absorption amount of from 50 to 70 g/100 g and 0.1 to 8 parts by weight of a silane coupling agent.