A power divider/combiner, comprising: a common terminal configured to receive input of a high frequency signal to be divided, or output a combined high frequency signal; a first input/output terminal and a second input/output terminal , which are configured to output a divided high frequency signal or receive input of a high frequency signal to be combined; a first quarter-wave impedance transformer including one end connected to the common terminal and another end connected to the first input/output terminal; a second quarter-wave impedance transformer including one end connected to the common terminal and another end connected to the second input/output terminal; an isolation resistor configured to prevent an interference between a high frequency signal of the first input/output terminal and a high frequency signal of the second input/output terminal; a first line configured to connect the isolation resistor and the first input/output terminal, and having a length that is an integer multiple of half a wavelength; and a second line configured to connect the isolation resistor and the second input/output terminal, and having a length that is an integer multiple of half a wavelength, wherein at least two or more of line portions of the first line and the second line have different impedances and are connected in cascade, wherein the first line includes a first stub at a line portion located on a side closer to the first input/output terminal than a center in a longitudinal direction of the first line, and wherein the second line includes a second stub at a line portion located on a side closer to the second input/output terminal than a center in a longitudinal direction of the second line. a common terminal configured to receive input of a high frequency signal to be divided, or output a combined high frequency signal; a first input/output terminal and a second input/output terminal , which are configured to output a divided high frequency signal or receive input of a high frequency signal to be combined; a first quarter-wave impedance transformer including one end connected to the common terminal and another end connected to the first input/output terminal; a second quarter-wave impedance transformer including one end connected to the common terminal and another end connected to the second input/output terminal; an isolation resistor configured to prevent an interference between a high frequency signal of the first input/output terminal and a high frequency signal of the second input/output terminal; a first line configured to connect the isolation resistor and the first input/output terminal, and having a length that is an integer multiple of half a wavelength; and a second line configured to connect the isolation resistor and the second input/output terminal, and having a length that is an integer multiple of half a wavelength, wherein at least two or more of line portions of the first line and the second line have different impedances and are connected in cascade, wherein the first line includes a first stub at a line portion located on a side closer to the first input/output terminal than a center in a longitudinal direction of the first line, and wherein the second line includes a second stub at a line portion located on a side closer to the second input/output terminal than a center in a longitudinal direction of the second line. <EOS>