A probe unit includes: a contact probe that comes into contact with, at both ends of a longitudinal length of the contact probe, each of electrodes that are contact targets; and a probe holder including a main body portion configured to hold the contact probe, the main body portion being insulating. The main body portion includes, formed therein: a holder hole configured to hold the contact probe inserted in the holder hole; and a counterbore portion drilled in at least part of an area around the holder hole, the area being on one of surfaces of the main body portion, the surfaces being near one end and another end of the contact probe, the counterbore portion having an inner wall surface that forms a hollow space and that is insulating.