The invention relates to a pump (1) for conveying of a fluid from an intake region (2) to an outlet region (3) which has a housing (4) and at least one rotor (6) which is arranged rotatable around an axis of rotation (5) and which can be driven by a driving element. To obtain a high degree of efficiency the pump according to the invention is characterized in that the rotor (6) has a bore (7), that a piston element (8) is arranged in the bore which can move along the longitudinal axis (L) of the bore and that a plurality of magnets (9, 9′, 9″, . . . ) or a ring magnet is arranged stationary in the housing (4), wherein the magnets or the ring magnet exert a magnetic attractive force on the piston element (8), wherein the magnets (9, 9′, 9″, . . . ) or a ring magnet are arranged in such a manner in the housing (4) that the piston element (8) carries out an oscillating movement (O) in the bore (7) during rotation of the rotor (6) around the axis (5) due to the magnetic attractive force.