An apparatus is capable of transmitting information via an uplink control channel in an Orthogonal Frequency Division Multiple Access (OFDMA) communication system. Uplink control information is encoded to obtain a predetermined bit string. A signal sequence corresponding to the predetermined bit string is generated. The signal sequence is cyclic-shifted according to a predetermined rule. The cyclic-shifted signal sequence is controlled according to a subframe length. Therefore, reception performance deterioration of an uplink control channel allocated to an irregular subframe can be minimized.