A method for transmitting an uplink control channel at a terminal in a Single Carrier Frequency Division Multiple Access (SC-FDMA)-based mobile communication system is provided. The transmission method includes receiving a control channel index allocated from a base station; transmitting control information at every symbol through a subband and a Zadoff-Chue sequence offset resource, which are mapped to the control channel index according to a first grouping rule; and transmitting control information through a subband and a Zadoff-Chue sequence offset resource, which are mapped to the control channel index according to a second grouping rule, beginning from a symbol after a slot boundary.