Disclosed is a wire harness arranging device which does not require a large installation space and has a simple configuration. The wire harness arranging device which arranges a harness (4) over the floor of an automobile and a seat provided slidably with respect to the floor comprises: a support body (7) which supports the seat; a protector (8) which leads the wire harness (4) to the seat; a rail to which the support body (7) and the protector (8) are attached slidably; and an extra length accommodating unit which accommodates the extra length portion of the wire harness (4). The protector (8) comprises: a support body fixing unit (89) to be fixed to the support body (7); and a wire harness attachment unit (80) to which the wire harness (4) is attached in a direction in which the center axis of the wire harness (4) is parallel to the sliding direction of the support body (7). The support body fixing unit (89) to be fixed to the support body (7) is disposed on the extended line of the center axis of the wire harness (4) attached to the wire harness attachment unit (80).