We present a spin-polarized scanning tunneling microscope (Sp-STM) for imaging the magnetic in-plane component of magnetic surfaces. Magnetic in-plane sensitivity is obtained by using a ferromagnetic ring as a Sp-STM tip. By periodically switching the magnetization of the ring, the spin-dependent tunneling current between the ring and a spin-polarized sample is measured. The topography and the spin polarization can be imaged at the same time. We resolved the 180^° domain wall of Fe whiskers and antiferromagnetic coupled Mn layers on Fe(001).