A wire routing device includes a wire housing part, a terminal housing chamber part, and a plurality of wire lead-out parts. The terminal housing chamber part includes a plurality of terminal housing chambers. Each of the wire lead-out parts couples one of the housing grooves with one of the terminal housing chambers. Each of wire surplus length absorption spaces is formed inside of a substantially rectangle abcd defined by a section bc of an outer wall of the voltage detection wire housing part located at a side of the terminal housing chamber and a section ad of a wall of the housing groove which faces the section bc, which are cut by a line ab and a line cd.