A unit comprising a wire fixing member to be fixed to a case in a state where at least one wire is inserted through at least one mounting hole of the case, wherein the wire fixing member is configured to hold the wire and comprises: at least one housing through which at least one wire insertion hole allowing the insertion of the wire penetrates, wherein a core is exposed at an end of the wire by stripping an insulation coating, a terminal fitting is connected to this exposed core, and a part of the wire is arranged between the wire fixing member and the terminal fitting; at least one first seal member which is provided to seal between the case and the housing; at least one second seal member which is provided to seal between the housing and the wire; and a retaining member which is held and retained in the housing in a state where the wire is fixed; wherein the retaining member is to be fixed on the outer peripheral surface of the wire, the housing includes an accommodating portion which at least partly accommodates the second seal member inside, a mounting portion into which the retaining member at least partly is mounted, and a partition wall which at least partly partitions between the accommodating portion and the mounting portion and through which at least one through hole allowing the passage of the wire penetrates, at least one front retainer for retaining the retaining member from a side opposite to the partition wall across the retaining member is mounted into the mounting portion, the retaining member includes a crimping portion to be crimped, bent or folded and connected to the wire and a holding tube portion behind and connected to the crimping portion, the crimping portion is sized to be able to be at least partly accommodated in the front retainer, and the holding tube portion is accommodated between the partition wall and the front retainer, characterized in that a fluidproof area which is made fluidproof by the first and second seal members (50, 40) is formed in a space of the wire insertion hole before the second seal member on a side of the wire insertion hole communicating with the interior of the case, the front retainer at least partly is mounted in a hole of the mounting portion which is a part of the fluid proof area, and the retaining member at least partly is arranged in the fluidproof area. at least one housing through which at least one wire insertion hole allowing the insertion of the wire penetrates, wherein a core is exposed at an end of the wire by stripping an insulation coating, a terminal fitting is connected to this exposed core, and a part of the wire is arranged between the wire fixing member and the terminal fitting; at least one first seal member which is provided to seal between the case and the housing; at least one second seal member which is provided to seal between the housing and the wire; and a retaining member which is held and retained in the housing in a state where the wire is fixed; wherein the retaining member is to be fixed on the outer peripheral surface of the wire, the housing includes an accommodating portion which at least partly accommodates the second seal member inside, a mounting portion into which the retaining member at least partly is mounted, and a partition wall which at least partly partitions between the accommodating portion and the mounting portion and through which at least one through hole allowing the passage of the wire penetrates, at least one front retainer for retaining the retaining member from a side opposite to the partition wall across the retaining member is mounted into the mounting portion, the retaining member includes a crimping portion to be crimped, bent or folded and connected to the wire and a holding tube portion behind and connected to the crimping portion, the crimping portion is sized to be able to be at least partly accommodated in the front retainer, and the holding tube portion is accommodated between the partition wall and the front retainer, characterized in that a fluidproof area which is made fluidproof by the first and second seal members (50, 40) is formed in a space of the wire insertion hole before the second seal member on a side of the wire insertion hole communicating with the interior of the case, the front retainer at least partly is mounted in a hole of the mounting portion which is a part of the fluid proof area, and the retaining member at least partly is arranged in the fluidproof area.