To provide a wafer prober adapted for testing a long IC with a probe card so improved as to have high reliability of inspecting an IC and long using life.

The wafer prober comprises a freely moving probing stage, a measuring board provided above the stage, and a plate-like probe card mounted at the lower side of the board. The card 40 is formed of a rectangular plate 41 having a rectangular opening 42 in such a manner that a plurality of probe pins 44 are extended from the opposed long sides 42a, 42b for partitioning the opening 42 toward the lower center of the opening. The pins are electrically connected to coupling pin 48 via wirings 46. The board is formed of a rectangular plate having a rectangular opening larger than the opening of the probe card. The probe card is so mounted at the board that the center of the opening of the probe card coincides with that of the opening of the board.