A protector with a sensor couples to a sliding door. A first end of an insert is inserted in and fills up a space on a hollow part of the protector. A second end of the insert includes a support member and a lid. Top ends of core wires and top ends of two leads are fit in first channels on the support member. Covered parts and a wire harness are fit in a second channel. The second channel is formed between the support member and the lid and is continuous with the first channels. The support member and the lid include feeding ports to receive and feed die-molding material into the second channel during die molding.