A probe unit for contacting an electrode of a contacted body and an electrode of a contact target at both ends in a longitudinal direction, the probe unit comprising: a plurality of conductive contact probes, each contacting the electrode of the contacted body at one end in the longitudinal direction; and a probe holder accommodating the plurality of contact probes, wherein each of the contact probes includes: a plunger including: a contact portion contacting the electrode of the contacted body; a flange portion extending from a base end of the contact portion and having a diameter larger than a diameter of the contact portion; a boss portion extending from an end of the flange portion different from an end continuing to the contact portion and having a diameter smaller than the diameter of the flange portion; and a base end portion extending from an end of the boss portion different from an end continuing to the flange portion and having a substantially same diameter with the boss portion; and a spring coil attached to the boss portion, the probe holder is made of a conductive material and includes a plurality of holder holes (33, 34), each having a stepped shape in which diameters at both ends in a thickness direction are decreased and accommodating the respective contact probes, the flange portion abuts one of step portions of the stepped shape, and the spring coil abuts another one of the step portions such that the spring coil biases the plunger, the spring coil being made of a conductive material having a resistance greater than that of the plunger or of an elastic and insulating material. a plurality of conductive contact probes, each contacting the electrode of the contacted body at one end in the longitudinal direction; and a probe holder accommodating the plurality of contact probes, wherein each of the contact probes includes: a plunger including: a contact portion contacting the electrode of the contacted body; a flange portion extending from a base end of the contact portion and having a diameter larger than a diameter of the contact portion; a boss portion extending from an end of the flange portion different from an end continuing to the contact portion and having a diameter smaller than the diameter of the flange portion; and a base end portion extending from an end of the boss portion different from an end continuing to the flange portion and having a substantially same diameter with the boss portion; and a plunger including: a contact portion contacting the electrode of the contacted body; a flange portion extending from a base end of the contact portion and having a diameter larger than a diameter of the contact portion; a contact portion contacting the electrode of the contacted body; a flange portion extending from a base end of the contact portion and having a diameter larger than a diameter of the contact portion; a boss portion extending from an end of the flange portion different from an end continuing to the contact portion and having a diameter smaller than the diameter of the flange portion; and a base end portion extending from an end of the boss portion different from an end continuing to the flange portion and having a substantially same diameter with the boss portion; and a spring coil attached to the boss portion, the probe holder is made of a conductive material and includes a plurality of holder holes (33, 34), each having a stepped shape in which diameters at both ends in a thickness direction are decreased and accommodating the respective contact probes, the flange portion abuts one of step portions of the stepped shape, and the spring coil abuts another one of the step portions such that the spring coil biases the plunger, the spring coil being made of a conductive material having a resistance greater than that of the plunger or of an elastic and insulating material.