Provided is a transmission line used to transmit high-frequency electrical signals which can remove a dip-shaped (S21) loss of transmission characteristics due to wall surface resonance, furthermore, can further decrease the size, and can suppress the manufacturing cost at a low level. The transmission line used to transmit high-frequency electrical signals (1) is made up of a signal line (3) used to transmit high-frequency electrical signals which is formed on a front surface (2a) of a dielectric substrate (2), GND electrodes (4) formed outside the signal line (3) and in vicinities of end portions of the front surface (2a), a GND electrode (6) that is electrically connected to the GND electrodes (4) through via holes (5) formed across an entire rear surface (2b) of the dielectric substrate (2), and band-shaped resistors (7) that are formed outside the GND electrodes (4) and in the end portions of the surface (2a) and are electrically connected to the GND electrodes (4).