The probe assembly has a plurality of probes, a probe base provided with the probes, and a plurality of guard members provided on the probe base. Each probe has an arm portion supported on the probe base at its one end and extending from a mounting surface of the probe base at a distance substantially along the mounting surface. At the other end of each arm portion is formed a tip projecting so as to project in a direction to be away from the mounting surface of the probe base. The guard member is supported on the probe base near at least one side of each arm portion. The guard surface is positioned in the vicinity of the height position of one surface and the opposite other surface of the arm portion opposing the mounting surface of the probe base.