A thermomagnetic cycle device comprising: a magneto-caloric element that emits or absorbs heat depending on an intensity of an external magnetic field; a magnetic field modulation device that modulates the external magnetic field applied to the magneto-caloric element; a heat transport device that generates a both-way flow of heat transport medium that exchanges heat with the magneto-caloric element so that a high temperature end and a low temperature end are generated in the magneto-caloric element; a phase controller (71, 72, 571, 572) that adjusts a phase difference between a magnetic field phase representing change in the external magnetic field generated by the magnetic field modulation device and a flow phase of the both-way flow generated by the heat transport device; and a control device that controls the phase controller, wherein the control device includes a phase acquisition part (18a, 918b, A18b) that acquires the flow phase (PHf) of the both-way flow of the heat transport medium or a reaction phase (PHtr) representing change in the heat emitted or absorbed by the magneto-caloric element, and characterized in that the thermomagnetic cycle device further comprises: a control part (18c, 918c) that controls the phase controller based on the flow phase or the reaction phase, wherein the phase controller is disposed between the magnetic field modulation device and the heat transport device, and controls the phase difference in a mechanical interlocking relation between the magnetic field modulation device and the heat transport device, wherein the phase controller is configured to correspond to an advance direction and a retard direction, and has a component (73, 74) that defines a plurality of capacity chambers (75, 76) in which operation fluid is arranged and wherein the control part controls the phase difference by controlling a ratio of volume between the plurality of capacity chambers. a magneto-caloric element that emits or absorbs heat depending on an intensity of an external magnetic field; a magnetic field modulation device that modulates the external magnetic field applied to the magneto-caloric element; a heat transport device that generates a both-way flow of heat transport medium that exchanges heat with the magneto-caloric element so that a high temperature end and a low temperature end are generated in the magneto-caloric element; a phase controller (71, 72, 571, 572) that adjusts a phase difference between a magnetic field phase representing change in the external magnetic field generated by the magnetic field modulation device and a flow phase of the both-way flow generated by the heat transport device; and a control device that controls the phase controller, wherein the control device includes a phase acquisition part (18a, 918b, A18b) that acquires the flow phase (PHf) of the both-way flow of the heat transport medium or a reaction phase (PHtr) representing change in the heat emitted or absorbed by the magneto-caloric element, and characterized in that the thermomagnetic cycle device further comprises: a control part (18c, 918c) that controls the phase controller based on the flow phase or the reaction phase, wherein the phase controller is disposed between the magnetic field modulation device and the heat transport device, and controls the phase difference in a mechanical interlocking relation between the magnetic field modulation device and the heat transport device, wherein the phase controller is configured to correspond to an advance direction and a retard direction, and has a component (73, 74) that defines a plurality of capacity chambers (75, 76) in which operation fluid is arranged and wherein the control part controls the phase difference by controlling a ratio of volume between the plurality of capacity chambers. a control part (18c, 918c) that controls the phase controller based on the flow phase or the reaction phase, wherein the phase controller is disposed between the magnetic field modulation device and the heat transport device, and controls the phase difference in a mechanical interlocking relation between the magnetic field modulation device and the heat transport device, wherein the phase controller is configured to correspond to an advance direction and a retard direction, and has a component (73, 74) that defines a plurality of capacity chambers (75, 76) in which operation fluid is arranged and wherein the control part controls the phase difference by controlling a ratio of volume between the plurality of capacity chambers.