Machine with an electromechanical converter, where a linear movable piston (30) is placed in a tubular cylinder casing (20). The piston supports a row of centrally placed annular permanent magnets (38) which produce an electromagnetic field of force. This is effective towards a surrounding row of annular coils (21). Such a machine can be driven as a motor or as a generator with a minimum of movable parts. At the ends of the closed cylinder is formed a chamber (40, 50), which forms a gas spring. In its simplest form the machine acts as a vibrator or as a vibration-driven generator. Additionally, to the gas springs, and at least at one end of the cylinder casing, can be placed a helical spring which ensures the central position of rest of the piston in the case of vertical installation. The piston can be connected to an axial bar (34) which is lead out of the machine on its one end for transmission of kinetic energy to or from the machine.