To provide a vehicle propelling device and a hydraulic transmission device having a controller for adjusting a pressure to compensate an actual fluctuation of hydraulic leak rate.

This vehicle propelling device includes a wheel motor and a hydraulic transmission device having a variable displacement type pump changing according to a pump flow amount command signal, decides an estimation motor flow rate, and outputs a signal 69 corresponding to the estimation motor flow rate. A pressure command signal 77 corresponds to a required pump pressure. A controller calculates a pump flow rate, compares an actually detected motor flow rate 75 with the pump flow rate, and decides a device leak rate 107. The controller adjusts the estimation motor flow rate signal 69 to compensate the leak rate 107 and generates an appropriate pump flow amount command signal.