Motorcycle steering system

The steering system (30) includes a steering unit (32) adapted to convert an operation input to an input shaft (33) into an arbitrary amount of rotation and/or an arbitrary turning force and output them/it from an output shaft (34). A steering handlebar (15) is coupled to the input shaft (33). A support bracket (4a) is coupled to the output shaft (34) and supports a front wheel (WF) of the vehicle (1). A housing (31) accommodates the steering unit (32), the housing (31) being mounted to a front end of a vehicle body frame (2) of a motorcycle (1) integrally therewith. The steering unit (32) includes a variable ratio steering mechanism (32b) adapted to convert an input steering angle into an arbitrary output steering angle and transmit it to the front wheel (WF), and a power assist mechanism (32a) adapted to supply an arbitrary supplementary force to an input operation. The housing (31) and the vehicle body frame (2) are made of the same material and welded together, or made of different materials and fixed together with bolts or the like.