Experiments were carried out using an ultraprecision lathe developed by the Precision Machining & Machine Tools Laboratory in KAIST in order to secure the mirror finishing of magnetic disks by face cutting. 35.34 nm (P-V R(max)) and 4.06 nm (R(a)) were obtained as the result of the experiments. Single-crystal diamond tools having tool nose radii of 1000, 200 and 20 mm were used. The effects of the tool nose radius, the feed and the depth of cut on the surface roughness were investigated. In face cutting, a relationship between the cutting force and the surface roughness in terms of the tool nose radius, the feed and the depth of cut is suggested to predict the surface roughness through frequency-domain analysis.