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 (1011, 1012), 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 (2111, 2121, 2201, 2301) 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 (2112, 2122, 2202, 2302) 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 (2111, 2121, 2201,2301) and the second line (2112, 2122, 2202, 2302) have different impedances and are connected in cascade, wherein the first line (2111, 2121, 2201, 2301) 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 (2112, 2122, 2202, 2302) 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 (1011, 1012), 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 (2111, 2121, 2201, 2301) 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 (2112, 2122, 2202, 2302) 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 (2111, 2121, 2201,2301) and the second line (2112, 2122, 2202, 2302) have different impedances and are connected in cascade, wherein the first line (2111, 2121, 2201, 2301) 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 (2112, 2122, 2202, 2302) 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.