A method and a device for transmitting/receiving control information in a wireless communication system are disclosed. A method of performing uplink transmission in a wireless communication system, according to one embodiment of the present disclosure, may comprise the steps of. receiving multicast PDSCHs on the basis of a plurality of G-RNTIs; receiving DCI for scheduling a PUSCH, wherein the DCI includes information on a T-DAI value for a HARQ-ACK codebook for a multicast; applying the T-DAI value per G-RNTI with respect to the plurality of G-RNTIs so as to determine a plurality of HARQ-ACK codebooks for the multicast PDSCHs; and transmitting HARQ-ACK information determined by concatenating the plurality of HARQ-ACK codebooks.