A link startup method of a storage device (30, 1300a, 1300b) connected to a host (20, 2100) through a plurality of lanes, wherein the method performed by the storage device comprises: performing an initialization operation (400, 500) in the storage device (30, 1300a, 1300b); establishing data communication through a connected transmission lane and a connected reception lane among the plurality of lanes; transmitting a high speed link up message to the host (20, 2100) through the connected transmission lane of the storage device (30, 1300a, 1300b); and performing a link startup operation in a high speed mode through the connected transmission lane of the storage device (30, 1300a, 1300b) and the connected reception lane of the host (20, 2100), based on the high speed link up message transmitted by the storage device (30, 1300a, 1300b), wherein the transmitting of the high speed link up message to the host (20, 2100) through the connected transmission lane of the storage device (30, 1300a, 1300b) includes transitioning a line in the connected transmission lane of the storage device (30, 1300a, 1300b) from a zero differential line voltage DIF-Z to an activate period (T ACTIVATE) having a negative differential line voltage DIF-N, wherein, when a length of the activate period (T ACTIVATE) is less than a second time, the connected transmission lane of the storage device (30, 1300a, 1300b) and the connected reception lane of the host (20, 2100) enter the high speed mode, and, when the length of the activate period (T ACTIVATE) is the second time or more, the connected transmission lane of the storage device (30, 1300a, 1300b) and the connected reception lane of the host (20, 2100) enter a low speed mode. performing an initialization operation (400, 500) in the storage device (30, 1300a, 1300b); establishing data communication through a connected transmission lane and a connected reception lane among the plurality of lanes; transmitting a high speed link up message to the host (20, 2100) through the connected transmission lane of the storage device (30, 1300a, 1300b); and performing a link startup operation in a high speed mode through the connected transmission lane of the storage device (30, 1300a, 1300b) and the connected reception lane of the host (20, 2100), based on the high speed link up message transmitted by the storage device (30, 1300a, 1300b), wherein the transmitting of the high speed link up message to the host (20, 2100) through the connected transmission lane of the storage device (30, 1300a, 1300b) includes transitioning a line in the connected transmission lane of the storage device (30, 1300a, 1300b) from a zero differential line voltage DIF-Z to an activate period (T ACTIVATE) having a negative differential line voltage DIF-N, wherein, when a length of the activate period (T ACTIVATE) is less than a second time, the connected transmission lane of the storage device (30, 1300a, 1300b) and the connected reception lane of the host (20, 2100) enter the high speed mode, and, when the length of the activate period (T ACTIVATE) is the second time or more, the connected transmission lane of the storage device (30, 1300a, 1300b) and the connected reception lane of the host (20, 2100) enter a low speed mode.