There is provided a terminal device that communicates with a base station apparatus. The terminal device includes means for setting a maximum output power value in uplink transmission to a first serving cell group based on a maximum output power value of the terminal device and an output power value for the first serving cell group in a case where the uplink transmission to the first serving cell group overlaps with uplink transmission to a second serving cell group in a certain timing, and means for setting a maximum output power value in the uplink transmission to the second serving cell group based on the maximum output power value of the terminal device, the output power value for the first serving cell group and a value for guaranteeing the uplink transmission to the first serving cell group.