A power amplifier comprising a Doherty amplifier, the Doherty amplifier comprising a carrier amplifier unit and a peak amplifier unit and being configured to amplify an input signal, wherein one of or both the carrier amplifier unit and the peak amplifier unit comprises: a plurality of dividing units (12, 22), signals propagating between first input ports and second output ports and between second input ports and first output ports of the respective plurality of dividing units (12, 22) having phases shifted by 90° from phases of signals propagating between the first input ports and the first output ports and between the second input ports and the second output ports of the respective plurality of dividing units (12, 22); a plurality of amplifiers configured to receive signals that have been obtained by dividing the input signal, to amplify the divided input signals that are in phase, and to output the amplified input signals respectively to the first input ports of the plurality of dividing units (12, 22); a combining unit (4, 30) configured to output a combined signal, the combined signal being obtained by combining a signal input to a third input port and a signal input to a fourth input port; a first combining and dividing unit configured to output a first combined signal to the third input port of the combining unit (4, 30), the first combined signal being obtained by combining signals from the first output ports of the respective plurality of dividing units (12, 22); a second combining and dividing unit configured to output a second combined signal to the fourth input port of the combining unit (4, 30), the second combined signal being obtained by combining signals from the second output ports of the respective plurality of dividing units (12, 22); and a plurality of transmission lines (L11, L12) configured to connect the plurality of amplifiers respectively to the first and second combining and dividing units (13, 23) by the same line length. a plurality of dividing units (12, 22), signals propagating between first input ports and second output ports and between second input ports and first output ports of the respective plurality of dividing units (12, 22) having phases shifted by 90° from phases of signals propagating between the first input ports and the first output ports and between the second input ports and the second output ports of the respective plurality of dividing units (12, 22); a plurality of amplifiers configured to receive signals that have been obtained by dividing the input signal, to amplify the divided input signals that are in phase, and to output the amplified input signals respectively to the first input ports of the plurality of dividing units (12, 22); a combining unit (4, 30) configured to output a combined signal, the combined signal being obtained by combining a signal input to a third input port and a signal input to a fourth input port; a first combining and dividing unit configured to output a first combined signal to the third input port of the combining unit (4, 30), the first combined signal being obtained by combining signals from the first output ports of the respective plurality of dividing units (12, 22); a second combining and dividing unit configured to output a second combined signal to the fourth input port of the combining unit (4, 30), the second combined signal being obtained by combining signals from the second output ports of the respective plurality of dividing units (12, 22); and a plurality of transmission lines (L11, L12) configured to connect the plurality of amplifiers respectively to the first and second combining and dividing units (13, 23) by the same line length.