A probe device includes an electrode plate arranged above a mounting table for mounting thereon a semiconductor wafer and electrically connected to a tester, a connection conductor arranged at a side of the mounting table and electrically connected to a mounting table electrode formed on a mounting surface of the mounting table, and a cleaning mechanism including a polishing unit for polishing a contact portion of the connection conductor, a brush cleaning unit for performing a brush-cleaning of the contact portion, and a contact resistance measuring unit for measuring a contact resistance of the contact portion. The mounting table electrode is in contact with a backside electrode of a semiconductor device of the semiconductor wafer. When the connection conductor is connected to the electrode plate, a backside electrode formed on a backside of the semiconductor device and the tester are electrically connected to each other.