A composite cable includes a plurality of power lines, one signal line unit, and a sheath collectively covering the plurality of power lines and the one signal line unit. The signal line unit includes a plurality of pairs of signal lines, and an inner sheath covering a first assembled article. The first assembled article is formed by arranging the signal lines to be paired at each pair of opposing vertices of a polygon with an even number of vertices in a cross-section perpendicular to a longitudinal direction of the signal line unit and twisting all the signal lines together.