A circuit body routing structure includes a circuit body routed, with respect to a vehicle body having a rocker on which a center pillar is erected, along the rocker. The circuit body is formed of a long flat conductor having a conductor portion of a flat cross-sectional shape. The circuit body includes a linear portion disposed overlapping an upper surface of the rocker, and a detour portion disposed overlapping a side surface of the rocker on a vehicle interior side or a side surface of the center pillar on the vehicle interior side at a junction between the rocker and the center pillar.