An in-plane magnetized spin-orbit magnetic device is provided. The in-plane magnetized spin-orbit magnetic device includes a heavy metal layer, an antiferromagnetic layer, and a magnetic tunnel junction. The antiferromagnetic layer is disposed on the heavy metal layer, and the magnetic tunnel junction is disposed on the antiferromagnetic layer. The magnetic tunnel junction includes a free layer, a barrier layer, and a pinned layer. The barrier layer is disposed on the free layer, and the pinned layer is disposed on the barrier layer. A film surface shape of the free layer is a rounded rectangle.