A probe device which is configured to be Z electrically connected to a semiconductor device formed on a semiconductor wafer (W) 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 (W); a mounting table electrode formed on a mounting surface of the mounting table on which the semiconductor wafer (W) 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 (W) 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 (W); a mounting table electrode formed on a mounting surface of the mounting table on which the semiconductor wafer (W) 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 (W) 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. <EOS>