This invention provides an oil-hydraulic vehicle whose driving force can be adjusted finely and which can be run smoothly and comfortably. The oil-hydraulic vehicle comprises a wheel-driving means 40 for driving a wheel 31, which includes an oil-hydraulic motor 45 to drive the wheel 31 and a means 41 for controlling the rotational frequency of the oil-hydraulic motor 45. The oil-hydraulic motor 45 includes an output shaft 45s on which the wheel 31 is mounted and a plurality of oil chambers 45a-45e. Each oil chamber contains (i) a driving cogwheel 46 which is mounted on, and drives, the output shaft 45s and (ii) a driven cogwheel 47 which engages with the driving cogwheel 46. The means 41 for controlling the rotational frequency of the oil-hydraulic motor 45 includes a housing 42 with a circular rotor chamber 42h in it and a rotor 43 fitted in the circular rotor chamber 42h for free rotation.