A transportation device comprising: a device body unit; a device moving unit provided on the device body unit for moving the transportation device; and a cargo loading unit provided on the device body unit for self-loading cargo, wherein the device body unit comprises: a first body as a main body; a second body provided on the first body and linked to the cargo loading unit; and a third body attached to the second body and linked to the device moving unit, wherein the device moving unit comprises: a steering unit provided on the device body unit to control a moving direction of the transportation device; and a tire provided on a connecting arm linked to the steering unit, wherein at least a selected tire of the device moving unit receives power from a driving unit, characterised in that the driving unit comprises: a reduction gear assembly comprising a housing to which the connecting arm is fixed and a rotor linked to a wheel to which the tire is attached; and a hydraulic motor attached to the housing and linked to the reduction gear assembly so as to provide power to the wheel linked to the rotor. a device body unit; a device moving unit provided on the device body unit for moving the transportation device; and a cargo loading unit provided on the device body unit for self-loading cargo, wherein the device body unit comprises: a first body as a main body; a second body provided on the first body and linked to the cargo loading unit; and a third body attached to the second body and linked to the device moving unit, wherein the device moving unit comprises: a steering unit provided on the device body unit to control a moving direction of the transportation device; and a tire provided on a connecting arm linked to the steering unit, wherein at least a selected tire of the device moving unit receives power from a driving unit, characterised in that the driving unit comprises: a reduction gear assembly comprising a housing to which the connecting arm is fixed and a rotor linked to a wheel to which the tire is attached; and a hydraulic motor attached to the housing and linked to the reduction gear assembly so as to provide power to the wheel linked to the rotor. a first body as a main body; a second body provided on the first body and linked to the cargo loading unit; and a third body attached to the second body and linked to the device moving unit, a steering unit provided on the device body unit to control a moving direction of the transportation device; and a tire provided on a connecting arm linked to the steering unit, wherein at least a selected tire of the device moving unit receives power from a driving unit, characterised in that the driving unit comprises: a reduction gear assembly comprising a housing to which the connecting arm is fixed and a rotor linked to a wheel to which the tire is attached; and a hydraulic motor attached to the housing and linked to the reduction gear assembly so as to provide power to the wheel linked to the rotor. a reduction gear assembly comprising a housing to which the connecting arm is fixed and a rotor linked to a wheel to which the tire is attached; and a hydraulic motor attached to the housing and linked to the reduction gear assembly so as to provide power to the wheel linked to the rotor.