Discloses are a method for a terminal for transmitting an uplink signal to a base station and an apparatus supporting the method in a licensed assisted access (LAA) system in which a base station or a terminal transmits listen-before-talk (LBT)-based signals. Specifically, disclosed are a method for a terminal transmitting an uplink signal by executing a particular LBT action and an apparatus supporting the method if the uplink signal is transmitted by the terminal by sharing a maximum channel occupancy time (MCOT) with a base station.