The present disclosure is related to a method, by a user equipment (UE), for transmitting uplink data through a preconfigured uplink resource (PUR) in a wireless communication system and apparatus therefor. According to the present disclosure, the method comprises, the UE receives, from a base station, PUR configuration information for uplink data transmission based on the PUR in a radio resource control (RRC) connected state; transitions from the RRC connected state to an RRC idle state; performing a timing advance (TA) update procedure based on whether a TA related to uplink transmission timing is valid; and transmits, to the base station, the uplink data on a first resource of the PUR, wherein, based on that a specific resource included in the PUR is included in a TA update performing interval, a transmission for the uplink data on the specific resource is dropped, and a value of a counter for release of the PUR is held regardless of dropping of the uplink data on the specific resource.