A method of electric wire routing includes: routing an electric wire in an electric wire routing path which is provided in a case and has a concave shape in a cross-sectional view; and covering an upper portion of the electric wire routing path with a cover. A pair of guide pins are inserted into a through hole formed in a bottom portion of the electric wire routing path in the case from below to a position above a side wall portion which forms the electric wire routing path. The electric wire is passed between the guide pins. The cover is assembled to the upper portion of the electric wire routing path while the guide pins are pulled out from the through hole .