A probe unit includes: a first contact probe configured to come in contact with a signal electrode; a second contact probe configured to come in contact with a ground electrode; a probe holder including a first holder hole through which the first contact probe passes, and a second holder hole through which the second contact probe passes; and a conductive floating member including a first through hole to which the first contact probe is inserted and the signal electrode is inserted, and a second through hole to which the second contact probe is inserted and the ground electrode is inserted. The probe holder is configured such that at least an inner circumferential surface of the first holder hole has an insulating property, and the probe unit has a coaxial structure in which central axes of the first contact probe and the first through hole are aligned with each other.