Coriolis sensor of a Coriolis measuring device designed to measure a mass flow or a density of a medium flowing through at least one measuring tube, said sensor comprising: the at least one measuring tube with an inlet (11.1) and an outlet (11.2), wherein said tube is designed to conduct the medium between the inlet and the outlet; a support body, which is designed to hold the at least one measuring tube, at least an exciter, which is designed to cause the at least one measuring tube to vibrate; at least two sensing elements, which are designed to measure, respectively, vibrations of at least one measuring tube; wherein at least an exciter and/or at least a sensing element each have a coil unit in each case with at least a coil (14.1), and a magnet unit, wherein the magnet unit and the coil unit are mobile in relation to one another, wherein the magnet unit has a holder (15.1) and at least a first magnet group (15.21) with at least a magnet (15.211, 15.212) and at least a second magnet group (15.22) with at least a magnet (15.221, 15.222), wherein the holder has a body (15.3) with a body longitudinal axis and a first end (15.31) and with a second end (15.32), wherein the first end has a front face (15.311), characterized in that the body has three notches (15.4) which extend in a parallel plane in relation to one another and perpendicular to the front face, wherein a central notch (15.41) is separated from an outer notch (15.42) by an intermediate wall (15.51), wherein each intermediate wall has an opening (15.6), wherein the openings are opposite the central notch, wherein the coil unit is arranged in the central notch at least in sections, and wherein the first magnet group is arranged in a first opening, and wherein the second magnet group is arranged in a second opening. the at least one measuring tube with an inlet (11.1) and an outlet (11.2), wherein said tube is designed to conduct the medium between the inlet and the outlet; a support body, which is designed to hold the at least one measuring tube, at least an exciter, which is designed to cause the at least one measuring tube to vibrate; at least two sensing elements, which are designed to measure, respectively, vibrations of at least one measuring tube; wherein at least an exciter and/or at least a sensing element each have a coil unit in each case with at least a coil (14.1), and a magnet unit, wherein the magnet unit and the coil unit are mobile in relation to one another, wherein the magnet unit has a holder (15.1) and at least a first magnet group (15.21) with at least a magnet (15.211, 15.212) and at least a second magnet group (15.22) with at least a magnet (15.221, 15.222), wherein the holder has a body (15.3) with a body longitudinal axis and a first end (15.31) and with a second end (15.32), wherein the first end has a front face (15.311), characterized in that the body has three notches (15.4) which extend in a parallel plane in relation to one another and perpendicular to the front face, wherein a central notch (15.41) is separated from an outer notch (15.42) by an intermediate wall (15.51), wherein each intermediate wall has an opening (15.6), wherein the openings are opposite the central notch, wherein the coil unit is arranged in the central notch at least in sections, and wherein the first magnet group is arranged in a first opening, and wherein the second magnet group is arranged in a second opening.