PURPOSE: To provide fine driving device of a simple structure and the light weight which can surely attain the slow speed driving of a heavy automatically governed vehicle AGV with high stopping accuracy and has the facilitated maintenance and the excellent resistance to the environment.

CONSTITUTION: A gear 1 connected directly to a main driving hydraulic motor 5 is provided together with a gear 2 which is connected to a slow speed hydraulic motor 6 via an internal hydraulic clutch 4, and a gear 3 which engages both gears 1 and 2 and is directly connected to an output shaft 7. Furthermore a driving neutral electromagnetic switch valve 8 is added to idle the motor 5 in a slow speed driving mode together with a hydraulic clutch electromagnetic switch valve 9, and a slow speed electromagnetic proportional valve 10 which controls the motor 6.