A radio terminal according to an embodiment includes a controller configured to control a random access procedure. The random access procedure includes first processing of transmitting a random access preamble to a base station, second processing of receiving a random access response from the base station, and third processing of performing uplink transmission to the base station based on the random access response. The controller is configured to notify, in the first processing or the third processing, the base station of an amount of uplink data in a transmission buffer of the radio terminal.