The present invention relates to a method for a terminal to execute a random access in a mobile communication system, and comprises the steps of: transmitting a random access preamble using a resource determined according to a random access setting for the terminal; and receiving a random access response including uplink approval information from a base station as a response to the preamble transmission, wherein the random access setting is determined by a group corresponding to the terminal from a first random access setting for a first terminal group or a second random access setting for a second terminal group, and a resource reserved for the second terminal group according to the second random access setting is used for transmission of the random access preamble or transmission of uplink data.