The present invention relates to a method for transmitting uplink data in a spectrum sharing wireless communication system wherein, in order to enhance uplink transmission efficiency in an LTE-U service, clear channel assessment (CCA) is performed on a user terminal so as to consider the hidden node problem, and channel occupation based on an uplink signal of another terminal is considered, wherein applied are: a method for generating and transmitting a random backoff counter value at a base station so that all terminals can equally use a channel connection parameter needed for transmitting an uplink subframe in an unlicensed band; and a downlink controlling method for scheduling an uplink multi-subframe.