To facilitate driving and prevent a fatigue in a neck by avoiding fluctuations of a helmet to left and right even in a wind (air flow) of a high relative speed thereby stabilizing the helmet. A wake stabilizer for the helmet has a right stabilizer (10R) and a left stabilizer (10L) provided symmetrically at the body wake flow portions (9) on the left and right sides of the helmet. Each of the left and right stabilizers (10R, 10L) has a side straightening face (15) extending from the side face position of the body wake flow portion (9) to the rear surface at such an angle as being fitted on the back of the helmet while being kept flat, and a wind separating portion (16) providing a longitudinal edge extending perpendicularly on a rear edge.