An electromagnetically actuated bicycle trainer, comprising: a base; a support assembly, disposed on the base, comprising a support arm mounted on the base and a fastening member, which is disposed at one end of the support arm away from the base and configured for fastening an axle of a pedaling wheel; characterised by a hysteresis resistance generating module, comprising an inner magnetic stationary member, an outer magnetic stationary member, a semi-hard magnetic rotating member disposed between the inner magnetic stationary member and the outer magnetic stationary member, and a conductive coil that receives electric power; the inner magnetic stationary member comprising an accommodating groove for accommodating the conductive coil, and an inner magnetic sensing region; the outer magnetic stationary member comprising an outer magnetic sensing region; the semi-hard magnetic rotating member being correspondingly disposed between the inner magnetic sensing region and the outer magnetic sensing region, and configured for rotating correspondingly to turning of the axle; the inner magnetic sensing region comprising a plurality of inner recesses disposed at an interval to form a plurality of inner magnetic portions; the outer magnetic sensing region comprising a plurality of outer recesses disposed at an interval to form a plurality of outer magnetic portions; the outer magnetic portions corresponding to positions of the inner recesses, and the inner magnetic portions corresponding to positions of the outer recesses; wherein, the conductive coil receives the electric power to sense opposite magnetisms generated by the outer magnetic portions and the inner magnetic portions, such that the semi-hard magnetic rotating member correspondingly generates magnetism and generates a hysteresis resistance when rotated. a base; a support assembly, disposed on the base, comprising a support arm mounted on the base and a fastening member, which is disposed at one end of the support arm away from the base and configured for fastening an axle of a pedaling wheel; characterised by a hysteresis resistance generating module, comprising an inner magnetic stationary member, an outer magnetic stationary member, a semi-hard magnetic rotating member disposed between the inner magnetic stationary member and the outer magnetic stationary member, and a conductive coil that receives electric power; the inner magnetic stationary member comprising an accommodating groove for accommodating the conductive coil, and an inner magnetic sensing region; the outer magnetic stationary member comprising an outer magnetic sensing region; the semi-hard magnetic rotating member being correspondingly disposed between the inner magnetic sensing region and the outer magnetic sensing region, and configured for rotating correspondingly to turning of the axle; the inner magnetic sensing region comprising a plurality of inner recesses disposed at an interval to form a plurality of inner magnetic portions; the outer magnetic sensing region comprising a plurality of outer recesses disposed at an interval to form a plurality of outer magnetic portions; the outer magnetic portions corresponding to positions of the inner recesses, and the inner magnetic portions corresponding to positions of the outer recesses; wherein, the conductive coil receives the electric power to sense opposite magnetisms generated by the outer magnetic portions and the inner magnetic portions, such that the semi-hard magnetic rotating member correspondingly generates magnetism and generates a hysteresis resistance when rotated.