To provide a characteristic impedance measuring instrument, having superior measurement efficiency which can measure multiple signal layers of a multilayered printed wiring board by temporarily arranging a probe at a specific position on the multilayered printed wiring board, when signal pins are arranged so that they can abut against respective corresponding signal measurement pads at a time, and characteristic impedance is measured as to the multiple signal layers of the multilayered printed wiring board.

This characteristic impedance measuring instrument 1 has a TDR meter 11, which sends an electrical signal to the multilayered printed wiring board 3, having a ground layer 32 and multiple signal layers 31 and receives the signal to measure the characteristic impedance and also displays the measurement result and the probe 2, which is electrically connected to the TDR meter 11. The probe 2 has the signal pins 21, which are made to abut against the signal measurement pads, electrically connected to the signal layers 31 of the multilayered printed wiring board 3 and a ground pin 22, which is made to abut against a grounding measurement pad 34 electrically connected to the ground layer 32. The respective signal pins 21 are arranged at a body part 25 of the probe 2, so that they can be made to abut against the respective corresponding signal measurement pads 33 in one time.