A driving apparatus for speed changing and steering of a vehicle consists of a first driving unit for speed changing in advancing and reversing and a second driving unit for steering, which are arranged in a longitudinal row and are attached to a vehicle chassis. Each of the first driving unit and the second driving unit has a common structure, which comprises a housing and an HST and left and right differential output shafts contained in the housing. A left first differential output shaft and a left second differential output shaft are connected with each other so as to be rotated in the same direction, and a right first differential output shaft and a right second differential output shaft are connected with each other so as to be rotated in opposite directions. Both first and second HSTs of the first driving unit and a second driving unit receives power from engine through a common single belt. A movable swash plate of a hydraulic pump of the first HST is connected to a speed change pedal and a movable swash plate of a hydraulic pump of the second HST is connected to a steering wheel.