A probe device which is configured to be Z electrically connected to a semiconductor device formed on a semiconductor wafer and configured to be connected to a tester to perform an electrical test of the semiconductor device, the probe device comprising: a mounting table configured to mount thereon the semiconductor wafer; a mounting table electrode formed on a mounting surface of the mounting table on which the semiconductor wafer is mounted, the mounting table electrode being configured to contact a backside electrode formed on a backside of the semiconductor device; a probe card arranged above the mounting table, the probe card having a plurality of probes configured to be electrically connected to the tester; a driving mechanism configured to drive the mounting table to make the probes contact electrodes of the semiconductor device of the semiconductor wafer mounted on the mounting table; an electrode plate arranged above the mounting table and configured to be electrically connected to the tester; and a connection conductor arranged at a side of the mounting table and electrically connected to the mounting table electrode, the connection conductor being connectable to the electrode plate, wherein when the connection conductor is connected to the electrode plate, the backside electrode and the tester are electrically connected to each other; characterised in that the probe device further comprises a cleaning mechanism including a polishing unit configured to polish a contact portion of the connection conductor adapted to be in contact with the electrode plate, a brush cleaning unit configured to perform a brush-cleaning of the contact portion, and a contact resistance measuring unit configured to measure a contact resistance of the contact portion. a mounting table configured to mount thereon the semiconductor wafer; a mounting table electrode formed on a mounting surface of the mounting table on which the semiconductor wafer is mounted, the mounting table electrode being configured to contact a backside electrode formed on a backside of the semiconductor device; a probe card arranged above the mounting table, the probe card having a plurality of probes configured to be electrically connected to the tester; a driving mechanism configured to drive the mounting table to make the probes contact electrodes of the semiconductor device of the semiconductor wafer mounted on the mounting table; an electrode plate arranged above the mounting table and configured to be electrically connected to the tester; and a connection conductor arranged at a side of the mounting table and electrically connected to the mounting table electrode, the connection conductor being connectable to the electrode plate, wherein when the connection conductor is connected to the electrode plate, the backside electrode and the tester are electrically connected to each other; characterised in that the probe device further comprises a cleaning mechanism including a polishing unit configured to polish a contact portion of the connection conductor adapted to be in contact with the electrode plate, a brush cleaning unit configured to perform a brush-cleaning of the contact portion, and a contact resistance measuring unit configured to measure a contact resistance of the contact portion.