A waterproof bioelectrode includes an electrode pad (101) to be mounted on a living body and a lead wire (110) to be connected to the electrode pad. The electrode pad includes a waterproof base (106) having an adhesive contacting surface and a hole substantially at its center, a waterproof seal member (105) which fixes the lead wire to a lower surface of the contacting surface of the base while covering the hole such that a detection electrode provided to a distal end of the lead wire is exposed from the hole of the waterproof base, and a conductive gel (103) arranged on the contacting surface to come into contact with the detection electrode.