A method for determining an uplink transmission timing of a user equipment which is configured with a plurality of cells in a wireless communication system, the method comprising: receiving (S161) timing advance, TA, configuration information from a base station; and determining (S162) an uplink transmission timing for each of two cells among the plurality of cells based on the TA configuration information, wherein the two cells are included in a group, and wherein: i) when the two cells comprise a first cell using a frequency division duplex, FDD, frame structure and a second cell using a time division duplex, TDD, frame structure and when the group includes only secondary cells, both an uplink transmission timing of the first cell and an uplink transmission timing of the second cell are determined by applying a same offset value regardless of frame structures of the first cell and the second cell and the same offset value is an offset value applied to a cell using the TDD frame structure, and ii) when the two cells comprise the first cell using the FDD frame structure and the second cell using the TDD frame structure and when the group includes a primary cell, an uplink transmission timing of the primary cell is determined based on the TA configuration information, and both an uplink transmission timing of the first cell and an uplink transmission timing of the second cell are determined to be the same as the uplink transmission timing of the primary cell. receiving (S161) timing advance, TA, configuration information from a base station; and determining (S162) an uplink transmission timing for each of two cells among the plurality of cells based on the TA configuration information, wherein the two cells are included in a group, and wherein: i) when the two cells comprise a first cell using a frequency division duplex, FDD, frame structure and a second cell using a time division duplex, TDD, frame structure and when the group includes only secondary cells, both an uplink transmission timing of the first cell and an uplink transmission timing of the second cell are determined by applying a same offset value regardless of frame structures of the first cell and the second cell and the same offset value is an offset value applied to a cell using the TDD frame structure, and ii) when the two cells comprise the first cell using the FDD frame structure and the second cell using the TDD frame structure and when the group includes a primary cell, an uplink transmission timing of the primary cell is determined based on the TA configuration information, and both an uplink transmission timing of the first cell and an uplink transmission timing of the second cell are determined to be the same as the uplink transmission timing of the primary cell. i) when the two cells comprise a first cell using a frequency division duplex, FDD, frame structure and a second cell using a time division duplex, TDD, frame structure and when the group includes only secondary cells, both an uplink transmission timing of the first cell and an uplink transmission timing of the second cell are determined by applying a same offset value regardless of frame structures of the first cell and the second cell and the same offset value is an offset value applied to a cell using the TDD frame structure, and ii) when the two cells comprise the first cell using the FDD frame structure and the second cell using the TDD frame structure and when the group includes a primary cell, an uplink transmission timing of the primary cell is determined based on the TA configuration information, and both an uplink transmission timing of the first cell and an uplink transmission timing of the second cell are determined to be the same as the uplink transmission timing of the primary cell. <EOS>