According to the invention, there is provided a steering damper (10) in which the interior of a cylinder (12) is divided into two oil chambers (A), (B) by a piston (14) which slides in the cylinder (12) as a steering operation takes place, an oil hole (15) is formed in the piston (14) for providing a communication between the two oil chambers (A), (B) and a bypass passageway (16) is provided for allowing oil in one (A or B) of the oil chambers to flow into the other oil chamber (B or A) by bypassing the oil hole (15), the motorcycle steering damper being characterized in that a subsidiary chamber (17) is defined at an intermediate position along the length of the bypass passageway (16), and in that a check ball (18) is provided in the subsidiary chamber (17).