There is provided a transmission apparatus having a transmission line into which a low-impedance part is inserted. The transmission apparatus includes a package having a first impedance, a first transmission line and a second transmission line respectively connected on either side of the package and having a second impedance different from the first impedance, and an intermediate section respectively disposed in a connection between the package and the first transmission line and in a connection between the package and the second transmission line. The intermediate section is adjusted to have an electrical length of λ/4 (where λ is an electromagnetic wavelength corresponding to a desired frequency) and an impedance that is intermediate between the first impedance and the second impedance.