A vehicular orientation detection system (1) for detecting an orientation of a vehicle (5) traveling a road surface (100S) where magnetic markers (10) are laid includes sensor units (11) which each include a plurality of magnetic sensors arrayed in a vehicle width direction and measure a lateral shift amount with respect to the magnetic markers (10) and a control unit (12) which computes a difference between lateral shift amounts measured with any one of the magnetic markers (10) by front and rear sensor units (11) positioned at two locations separated in a longitudinal direction of the vehicle (5).