To extend responsiveness to work by making it possible to separately dispose a hydraulic pump 29 and a motor 30 at desired positions in a machine body of a work machine or the like using conventional ones for the hydraulic pump 29 and the motor 30, and easily improve work efficiency by freely securing necessary work speed ranges, in which the work speed range on the load side is also easily secured by use of a multi-stage transmission mechanism 111 to make forward and reverse driving possible when used for driving.

It is provided with a hydraulic type continuously variable transmission 19 to synchronously rotate an output shaft 47 of a hydraulic motor 30 with an input shaft 36 of the hydraulic pump 29 when a swash plate 31 of the hydraulic pump 29 of a variable displacement type is neutral, and accelerate/decelerate rotation of the output shaft 47 of the hydraulic motor 30 to rotation of the input shaft 36 of the hydraulic pump 29 in accordance with inclination of the swash plate 31 when the swash plate 31 is not neutral. The multi-stage transmission mechanism 111 is also provided between the input shaft 36 of the hydraulic pump 29 and the hydraulic motor 30.