An in-plane magnetized spin-orbit magnetic device is provided. The in-plane magnetized spin-orbit magnetic device includes a heavy metal layer, an upper electrode and a magnetic tunnel junction. The magnetic tunnel junction is disposed between the heavy metal layer and the upper electrode. The magnetic tunnel junction includes a free layer and a pinned layer. The free layer is disposed on the heavy metal layer, and the free layer has a first film plane area. The pinned layer is disposed on the free layer, and the pinned layer has a second film plane area. There is a preset angle between a long axis direction of a film plane shape of the free layer and a long axis direction of a film plane shape of the pinned layer, and the first film plane area is larger than the second film plane area.