We have developed a magneto-optical Kerr microscope that allows us to measure the ultrafast magnetization dynamics of ferromagnetic nanostructures. The magneto-optical signal can be recorded in a confocal reflection geometry with an accurate selection of the polarization. The magnetization dynamics is obtained from pump–probe measurements using frequency nondegenerate collinear pump and probe beams with a temporal resolution of $180\mathrm{fs}$ . Both probe and pump beams are focused to their diffraction limit, leading to an overall spatial resolution of $600\mathrm{nm}$ . The efficiency of the apparatus is tested by investigating the magnetization dynamics of individual $\mathrm{Co}{\mathrm{Pt}}_3$ disks with a submicrometer diameter and a thickness of $15\mathrm{nm}$ .