Provided are a method and a device for transmitting data in a wireless communication system. More particularly, a terminal transmits a first transmission preamble and a second transmission preamble so as to estimate an uplink channel. If a common temporary identifier is assigned to the first and second transmission preambles, a common response message for the first and second transmission preambles is received. If temporary identifiers that are different from each other are respectively assigned to the first and second transmission preambles, respective individual response messages for the first and second transmission preambles are received. Data is transmitted by means of an estimated uplink channel. The first transmission preamble is transmitted in a plurality of resource regions, and the second transmission preamble is transmitted in one resource region.