A terminal device comprising: processor circuitry configured to: perform dual connectivity with a first cell group and a second cell group different from the first cell group, control transmission power sharing between the first cell group and the second cell group in a synchronous LTE-NR-DC scenario, calculate a first transmission power amount of the first cell group with reference to parameters including a number of resource blocks, path loss and an allowable maximum transmission power amount, as well as a first maximum guaranteed power amount that is available for uplink toward the first cell group, which is notified using a first radio resource control "RRC" signaling from a radio base station device, and a second transmission power amount of the second cell group with reference to parameters including a number of resource blocks, path loss, and the allowable maximum transmission power amount, as well as a second maximum guaranteed power amount that is available for uplink toward the second cell group, which is notified using a second radio resource control "RRC" signaling from a radio base station device, and when transmissions of the first cell group overlap in time with transmissions of the second cell group and the first transmission power amount of the first cell group includes a first excess amount within the allowable maximum transmission power amount that is available to the terminal device for the first cell group and the second cell group, the first excess amount calculated by subtracting the first transmission power amount from the first maximum guaranteed power amount that is available for uplink toward the first cell group, reduce a transmission power amount of a slot that is used for transferring data using the uplink toward the first cell group by allocating the first excess amount to a slot that is used for transferring data using the uplink toward the second cell group during the overlapping time such that the total amount of the first transmission power amount of the first cell group and the second transmission power amount of the second cell group is within the allowable maximum transmission power amount; and a receiver configured to receive a signal of the first cell group and the second cell group. processor circuitry configured to: perform dual connectivity with a first cell group and a second cell group different from the first cell group, control transmission power sharing between the first cell group and the second cell group in a synchronous LTE-NR-DC scenario, calculate a first transmission power amount of the first cell group with reference to parameters including a number of resource blocks, path loss and an allowable maximum transmission power amount, as well as a first maximum guaranteed power amount that is available for uplink toward the first cell group, which is notified using a first radio resource control "RRC" signaling from a radio base station device, and a second transmission power amount of the second cell group with reference to parameters including a number of resource blocks, path loss, and the allowable maximum transmission power amount, as well as a second maximum guaranteed power amount that is available for uplink toward the second cell group, which is notified using a second radio resource control "RRC" signaling from a radio base station device, and perform dual connectivity with a first cell group and a second cell group different from the first cell group, control transmission power sharing between the first cell group and the second cell group in a synchronous LTE-NR-DC scenario, calculate a first transmission power amount of the first cell group with reference to parameters including a number of resource blocks, path loss and an allowable maximum transmission power amount, as well as a first maximum guaranteed power amount that is available for uplink toward the first cell group, which is notified using a first radio resource control "RRC" signaling from a radio base station device, and a second transmission power amount of the second cell group with reference to parameters including a number of resource blocks, path loss, and the allowable maximum transmission power amount, as well as a second maximum guaranteed power amount that is available for uplink toward the second cell group, which is notified using a second radio resource control "RRC" signaling from a radio base station device, and when transmissions of the first cell group overlap in time with transmissions of the second cell group and the first transmission power amount of the first cell group includes a first excess amount within the allowable maximum transmission power amount that is available to the terminal device for the first cell group and the second cell group, the first excess amount calculated by subtracting the first transmission power amount from the first maximum guaranteed power amount that is available for uplink toward the first cell group, reduce a transmission power amount of a slot that is used for transferring data using the uplink toward the first cell group by allocating the first excess amount to a slot that is used for transferring data using the uplink toward the second cell group during the overlapping time such that the total amount of the first transmission power amount of the first cell group and the second transmission power amount of the second cell group is within the allowable maximum transmission power amount; and a receiver configured to receive a signal of the first cell group and the second cell group.