PURPOSE: An automatic pumping hydro-pneumatic strut unit is provided to enable replacement of the strut unit with a standard vibration damper by exceedingly reducing the outside diameter. CONSTITUTION: An automatic pumping hydro-pneumatic strut unit(1) has an inner level regulation device. The automatic pumping hydro-pneumatic strut unit includes a working cylinder(24) arranged to a high-pressure chamber(4) in a vehicle and a piston pump transferring oil from a low-pressure chamber(5) to working chambers(29) connected to the high-pressure chamber. The working cylinder receives pressure of at least one gas padding acting like a spring. The working cylinder is divided into two working chambers by a working piston supported by an empty piston rod(8) filled with oil. The piston pump is propelled by spring motion. The piston pump connects the low-pressure chamber to the working chamber connected to the high-pressure chamber through a regulation hole closing according to the position of the working piston in the working cylinder. A flow connection extended through a partition wall(3) to the lower side of an oil level is arranged between a pump chamber and the low-pressure chamber. The flow connection is arranged to the partition wall. At least one bore for receiving a suction pipe(11) is formed to the low-pressure chamber area.