A method of transmitting an acknowledgement (ACK)/non-acknowledgement (NACK) signal in a wireless communication system is provided. The method includes: allocating a radio resource; and transmitting the ACK/NACK signal through an ACK channel in a location determined by an index for the radio resource, wherein the radio resource includes at least one resource unit which is a basic unit for resource allocation, the resource unit is at least one of a localized resource unit including subcarriers contiguous in a frequency domain and a distributed resource unit including subcarriers distributed in the frequency domain, an index of the localized resource unit is directly mapped to an index of the ACK channel, and an index of the distributed resource unit is mapped to an index of the ACK channel according to a permutation rule.